Apparatus and methods for warming and cooling bodies

ABSTRACT

A flexible heat exchanger is suitable for heating or cooling living subjects or objects. The heat exchanger has a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. A flexible heat exchange plate that is essentially impermeable to the heat exchange fluid is penetrated by substantially rigid thermally-conductive members. The members provide paths of high thermal conductivity through the plate. The heat exchange fluid may be water.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of PCT patent application No.PCT/CA2004/001660 filed on 22 Sep. 2004 which is a continuation-in-partof U.S. application Ser. No. 10/665,073 filed on 22 Sep., 2003 andentitled FLEXIBLE HEAT EXCHANGERS FOR MEDICAL COOLING AND WARMINGAPPLICATIONS, Ser. No. 10/665,074 filed on 22 Sep., 2003 and entitledFLEXIBLE HEAT EXCHANGERS pursuant to 35 U.S.C. § 120. PCT patentapplication No. PCT/CA2004/001660 also claims the benefit of U.S. patentapplication 60/565,517 filed on 27 Apr. 2004 and entitled FLEXIBLE HEATEXCHANGERS, 60/565,537 filed on 27 Apr. 2004 and entitled FLEXIBLE HEATEXCHANGERS FOR MEDICAL COOLING AND WARMING APPLICATIONS, and 60/580,356filed on 18 Jun. 2004 and entitled METHOD AND APPARATUS FOR AFFIXINGTHROUGH MEMBER IN MEMBRANE, all of which are hereby incorporated byreference herein. This application claims the benefit of U.S.application No. 60/663,267 filed on 21 Mar. 2005 pursuant to 35 U.S.C. §119.

TECHNICAL FIELD

The invention relates to heat exchangers. The invention has particularapplication to heat exchangers for use in warming or cooling livingsubjects. The invention may be applied to cooling the brains or otherbody parts of living subjects. The apparatus and methods generallyprovide a heat exchange fluid, which is a liquid in some embodiments anda gas in other embodiments, that passes through a heat exchanger toexchange heat with a body to be warmed or cooled.

BACKGROUND

It has been discovered that quickly inducing hypothermia cansignificantly improve the recovery prospects of patients who sufferglobal ischemic brain injury secondary to cardiac arrest and probablyfocal ischemic brain injury from thrombotic or embolic causes. Thelatter is referred to as an ischemic stroke. Some trials have placedglobal and focal ischemic brain damaged victims in whole-body coolingchambers or devices. Intra vascular devices are used for whole bodycooling and, secondarily, brain cooling. Such chambers or devices areunwieldy and can be intimidating for the patient. Fletcher, U.S. Pat.No. 6,511,502 discloses methods for cooling a subject's brain byapplying heat exchangers to the neck of the subject adjacent thesubject's carotid arteries. The heat exchangers cool blood flowing tothe subject's brain.

In various other areas of medicine it is desirable to cool or warm bodyparts. For example, U.S. Pat. Nos. 4,138,743; 5,916,242; 4,566,455;4,750,493; 4,763,866; 4,020,963; 5,190,032; 5,486,204; 5,643,336;5,897,581; 5,913,855; 5,057,964; and 6,030,412 relate to cooling orwarming body.

Various types of heat exchanger exist. Air cooled heat sinks arestructures which take heat from an object and dissipate the heat intoambient air. Such heat sinks typically consist of a finned piece ofthermally-conductive material having a face which can be placed inthermal contact with an object, such as an electronic component, to becooled. Some heat sinks are equipped with fans located to flow air pastthe fins to improve the rate at which heat is dissipated.

U.S. Pat. No. 6,549,411 B1 discloses a flexible heat sink that can beattached to a generally flat surface of an object. The heat sink canflex to conform to the surface of the object to achieve improved contactwith the object, and hence increase the efficiency of heat transferbetween the heat sink and the object. U.S. Pat. No. 6,367,541 B2discloses a heat sink that can be attached to multiple electronic chipswhich have different heights. The heat sink dissipates heat from thechips into ambient air. The devices disclosed in these patents are notsuitable for heating or cooling living subjects.

U.S. Pat. No. 5,368,093 discloses a flexible bag filled with thermaltransfer fluid useful for thawing frozen foods. U.S. Pat. No. 4,910,978discloses a flexible pack containing a gel. The pack can be cooled andapplied to a patient for cold therapy. The pack conforms to surfacecontours of the patient's body. These devices have limited coolingcapacities.

More sophisticated heat exchangers use a heat exchange fluid such as acooling or heating liquid instead of ambient air to carry heat away fromor provide heat to an object to be cooled or heated. Golden, U.S. Pat.No. 4,864,176 discloses a thermal bandage. The bandage includes aconforming member adapted to be placed against the skin. A thermal packincludes a chamber through which fluid can be circulated. The thermalpack is separated from the conforming member by a thermally-conductivesurface. U.S. Pat. No. 5,757,615 discloses a flexible heat exchangerwith circulating water as coolant for cooling a notebook computer. U.S.Pat. No. 5,643,336 discloses a flexible heating or cooling pad withcirculating fluid for therapeutically treating the orbital, frontal,nasal and peri-oral regions of a patient's head. U.S. Pat. No. 6,551,347B1 discloses a flexible heat exchange structure having fluid-conductingchannels formed between two layers of flexible material for heat/coldand pressure therapy. U.S. Pat. Nos. 6,197,045 B1 and 6,375,674 B1disclose a flexible medical pad with an adhesive surface for adheringthe pad to the skin of a patient. U.S. Pat. No. 6,030,412 discloses aflexible enveloping member for enveloping a head, neck, and upper backof a mammal for cooling the brain of the mammal suffering a braininjury. All of these heat exchangers require heat to pass through alayer of some flexible material such as rubber, a thermoplastic, or aflexible plastic such as polyurethane. In addition, heat is exchangedbetween the surface of the flexible material and circulating fluid.Water is the most commonly used circulating fluid.

Rubber and flexible plastics are poor conductors of heat. To provide ahigh heat transfer efficiency in a flexible heat exchanger in which heatis transferred across a layer of rubber or plastic the layer must bevery thin. This makes such heat exchangers prone to damage. In addition,water is a poor heat conductor. Heat exchange between the flexiblematerial and water is largely dependent on convection. Water flowingover a relatively flat surface will often not result in efficient heatexchange.

U.S. Pat. No. 3,825,063 discloses a heat exchanger having metal screensof fine mesh with internal plastic barriers that at least partlypenetrate the screens. The screens are stacked to provide transverseheat conduction relative to longitudinal flow paths. U.S. Pat. No.4,403,653 discloses a heat transfer panel comprising a woven wire meshcore embedded in a layer of plastic material. The mesh and closure layerextend in the same longitudinal direction. U.S. Pat. No. 5,660,917discloses a sheet with electrically insulating thermal conductorsembedded in it. The apparatus disclosed in those patents is not adaptedfor warming or cooling living subjects.

There remains a need for heat exchangers suitable for warming or coolingliving subjects via the surface of the subjects' skin. There is aparticular need for such heat exchangers that provide a high ratio ofheat-transfer capacity to skin contact area. There is also a need forheat exchangers which can be used in practising the methods described inFletcher, U.S. Pat. No. 6,511,502 and which avoid at least somedisadvantages of prior heat exchangers. In some fields there remains aneed for heat exchangers capable of providing high heat transfer ratesbetween the heat exchangers and objects that are not flat, are vibratingor are otherwise difficult to interface to. There is a particular needfor such heat exchangers which have high ratio of heat-transfer capacityto contact area.

SUMMARY OF THE INVENTION

The invention relates to heat exchangers and has many aspects which maybe combined or, in some cases, exploited individually. One aspect of theinvention provides a flexible heat exchanger comprising a volume havingat least one inlet for receiving a heat exchange fluid and at least oneoutlet and a flexible sheet essentially impermeable to the heat exchangefluid. The sheet carries a plurality of substantially-rigid members.Each of the members comprises an exposed thermally-conductive surface ona thermally-conductive first body on an outside of the sheet and havinga thermally-conductive portion extending from the thermally-conductivefirst body, through the sheet, and into the volume. Each of theplurality of members comprising opposed gripping surfaces held firmlyagainst opposed sides of the sheet.

Another aspect of the invention provides a flexible heat exchangercomprising a volume having at least one inlet for receiving a heatexchange fluid and at least one outlet. The volume has a flexible wallessentially impermeable to the heat exchange fluid. The wall carries aplurality of substantially-rigid members. Each of the members comprisinga thermally-conductive surface on an outside of the wall and has athermally-conductive portion extending from the thermally-conductivesurface, through the wall and into the volume. The thermally-conductingsurface is supported at a location spaced outwardly apart from anoutside surface of the wall.

Another aspect of the invention provides a flexible heat exchangesurface for use in a heat exchanger. The flexible heat exchange surfacecomprises a flexible sheet essentially impermeable to the heat exchangefluid. The sheet carries a plurality of substantially-rigid memberssealed to the sheet. Each of the members comprises first and secondthermally-conductive bodies exposed on first and second sides of thesheet. The first and second thermally-conductive bodies are connected bya narrowed thermally-conductive portion having a cross sectional areasmaller than a cross sectional area of either of the first and secondbodies. The thermally-conductive portion extends through an aperture inthe sheet.

Another aspect of the invention provides a flexible heat exchangercomprising a volume having at least one inlet for receiving a heatexchange fluid and at least one outlet. The volume has a flexible wallessentially impermeable to the heat exchange fluid. The wall carries aplurality of substantially-rigid members. Each of the members comprisesa thermally-conductive surface on an outside of the wall and has athermally-conductive portion extending from the pad, through the walland into the volume. The thermally-conducting surface is either flushwith or projects outwardly from an outside surface of the wall.

Another aspect of the invention provides a method for making a heatexchange surface for use in a heat exchanger. The method comprisesproviding a sheet, the sheet being essentially impervious to a heatexchange fluid to be used in the heat exchanger; insertingthermally-conductive members through the sheet; and, deforming at leastone end of each of the thermally-conductive members to cause thethermally-conductive member to sealingly engage the sheet.

Another aspect of the invention provides a method for cooling or warminga plurality of thermally-conductive heat exchange surfaces suitable forplacement against the skin of a living subject to cool or warm theliving subject. The method comprises: establishing a turbulent flow of aheat exchange fluid through a volume; allowing the heat exchange fluidto contact and exchange heat with a plurality of thermally-conductivemembers projecting into the volume through a flexible wall of thevolume, the thermally-conductive members each in direct thermal contactwith at least one of the heat exchange surfaces by way of an unbrokenpath of a material or materials having a thermal conductivity of atleast 50 Wm⁻¹K⁻¹; and, allowing heat to flow between the heat exchangesurfaces and the thermally-conductive members along the paths.

Another aspect of the invention provides a flexible heat exchanger forwarming or cooling a living subject. The heat exchanger comprises avolume having at least one inlet for receiving a heat exchange fluid andat least one outlet; and, a flexible heat exchange plate essentiallyimpermeable to the heat exchange fluid, the plate comprising a pluralityof substantially rigid thermally-conductive members extending through aflexible material of the plate from an outside surface of the plate intothe volume, the thermally-conductive members each projecting into avolume by a distance of at least 2 mm.

Another aspect of the invention provides a flexible heat exchangercomprising a volume having at least one inlet for receiving a heatexchange fluid and at least one outlet; and, a flexible plateessentially impermeable to the heat exchange fluid. The plate comprisesan array of closely-spaced apart substantially rigid metalthermally-conductive members extending through a flexible material ofthe plate, substantially at right angles to inner and outer surfaces ofthe plate, from an outside surface of the plate into the volume whereina total area of the thermally-conductive members exposed on the outersurface of the plate exceeds a total cross sectional area of thethermally-conductive members at a point where the cross sectionalmembers are extending through the flexible material.

Another aspect of the invention provides apparatus for warming orcooling a living subject, the apparatus comprising a plurality of heatexchangers and a mechanism for independently regulating a supply ofcooling or warming fluid circulated through each of the heat exchangers.One aspect of the invention provides a flexible heat exchanger forwarming or cooling a living subject. The heat exchanger comprises avolume having at least one inlet for receiving a heat exchange fluid andat least one outlet. A heat exchange fluid may be circulated through thevolume. The heat exchanger comprises a flexible heat exchange plateessentially impermeable to the heat exchange fluid. The plate comprisesa flexible fluid-impervious membrane supporting a plurality ofsubstantially rigid thermally-conductive members. Thethermally-conductive members extend through the membrane from an outsidesurface of the plate into the volume. Each of the thermally-conductivemembers comprises a body, a portion extending through the membrane fromthe body and a retainer member on a side of the membrane opposite to thebody. The membrane is gripped between the body and the retainer member.

Another aspect of the invention provides a flexible heat exchanger. Theheat exchanger comprises a volume having at least one inlet forreceiving a heat exchange fluid and at least one outlet. A heat exchangefluid, for example, water, can flow through the volume. A flexible heatexchange plate essentially impermeable to the heat exchange fluid has aplurality of substantially rigid thermally-conductive members. Thethermally-conductive members extend through a flexible material of theplate from an outside surface of the plate into the volume. Thethermally-conductive members conduct heat between a subject and the heatexchange fluid.

Another aspect of the invention provides systems for heating or coolinga subject. The systems have a reservoir holding heat exchange fluid anda pair of feed pumps. One feed pump is connected to deliver the heatexchange fluid to a heat exchanger. Another feed pump is connected towithdraw the heat exchange fluid from the heat exchanger. The rate atwhich the heat exchange fluid is introduced into the heat exchanger bythe first feed pump is balanced with the rate at which fluid iswithdrawn from the heat exchanger by the second feed pump to maintain apressure within a volume in the heat exchanger within a desired range ofan ambient pressure.

One aspect of the invention provides a flexible heat exchanger. The heatexchanger comprises a volume having at least one inlet for receiving aheat exchange fluid and at least one outlet. A heat exchange fluid maybe circulated through the volume. The heat exchanger comprises aflexible heat exchange plate essentially impermeable to the heatexchange fluid. The plate comprises a flexible fluid-impervious membranesupporting a plurality of substantially rigid thermally-conductivemembers. The thermally-conductive members extend through the membranefrom an outside surface of the plate into the volume. Each of thethermally-conductive members comprises a body, a portion extendingthrough the membrane from the body and a retainer member on a side ofthe membrane opposite to the body. The membrane is gripped between thebody and the retainer member.

Another aspect of the invention provides a flexible heat exchanger. Theheat exchanger comprises a volume having at least one inlet forreceiving a heat exchange fluid and at least one outlet. A heat exchangefluid, for example, water, can flow through the volume. A flexible heatexchange plate essentially impermeable to the heat exchange fluid has aplurality of substantially rigid thermally-conductive members. Thethermally-conductive members extend through a flexible material of theplate from an outside surface of the plate into the volume. Thethermally-conductive members conduct heat between a subject and the heatexchange fluid.

Another aspect of the invention provides systems for heating or coolingan object. The systems have a reservoir holding heat exchange fluid anda pair of feed pumps. One feed pump is connected to deliver the heatexchange fluid to a heat exchanger. Another feed pump is connected towithdraw the heat exchange fluid from the heat exchanger. The rate atwhich the heat exchange fluid is introduced into the heat exchanger bythe first feed pump is balanced with the rate at which fluid iswithdrawn from the heat exchanger by the second feed pump to maintain apressure within a volume in the heat exchanger within a desired range ofan ambient pressure.

Another aspect of the invention provides a heat exchanger comprisingfront and rear sheet portions substantially impermeable to a heatexchange fluid. The front sheet portion supports a plurality ofsubstantially rigid thermally-conductive members extending through thefront sheet portion and having inner portions projecting into a volumebetween the front sheet portion and the rear sheet portion. Thethermally-conducting members have exposed thermally-conducting surfaceson a front side of the front sheet portion. The rear sheet portion isformed with indentations receiving each of the inner portions of theplurality of thermally-conductive members.

Other aspects of the invention provides flexible heat exchangeinterfaces. The interfaces have plates or membranes penetrated bysubstantially rigid thermally-conductive members. Thethermally-conductive members have enlarged pads on at least one side ofthe plate or membrane. The flexible material allows the interfaces toflex while the thermally-conductive members are operative to channelheat from a higher-temperature side of the interface to alower-temperature side of the interface.

Another aspect of the invention provides a flexible heat exchangercomprising a volume having an inlet and an outlet. The volume canreceive a heat exchange fluid, for example, water or a water-basedcoolant. The heat exchanger includes a flexible plate. Substantiallyrigid thermally-conductive members extend through a flexible material ofthe flexible plate from an outside surface of the flexible plate intothe volume.

In preferred embodiments the thermally-conductive members each have athermal conductivity of at least 50 Wm¹K¹ and preferably at least 100Wm¹K¹. The thermally-conductive elements may be made of materials suchas aluminum, copper, gold, silver, alloys of two or more of aluminum,copper, gold, or silver with one another, alloys of one or more ofaluminum, copper, gold, or silver with one or more other metals, carbon,graphite, diamond, or sapphire.

The thermally-conductive members may cover a substantial portion of theouter surface of the flexible heat exchange plate in some embodiments.For example, the thermally-conductive members may be exposed in an areaof 30% or 40% or more of an area of the flexible heat exchange plate. Insome embodiments, at least 50%, at least 70% or even at least 80% of anarea of the flexible heat exchange plate is covered by thethermally-conductive members. Because of the very high rate at whichheat can be carried through a thermally- conductive member, in somecases a coverage of 20% or even less by the thermally-conductive membersis sufficient.

The flexible material of the plate sheet or membrane may comprise, forexample, a suitable grade of polyurethane or other suitablethermoplastic polymer. Examples of other materials that may be suitablefor use as the plate of membrane include: styrenic copolymers; suitablegrades of: polyvinyl chloride (PVC); polyolefins such as polyethylene orpolypropylene; styrenics such as polystyrene; polyesters such aspolyethylene terephthalate (PET); polyethers such aspolyetheretherketone (PEEK); polyamides (e.g. NYLON™); silicone;cellophane; cellulose acetates; natural or synthetic rubbers;ethylene-vinyl acetate; neoprene; polytetrafluoroethylene (PTFE e.g.TEFLON™); plasticized metallic films; a combination of two or more ofthese materials; coated or impregnated fabrics; and the like. In someembodiments the flexible material has a thermal conductivity notexceeding 5 Wm⁻¹K⁻¹.

A further aspect of the invention provides a temperature control systemcomprising a heat exchanger according to the invention, a reservoircontaining a heat exchange fluid; a first feed pump connected to feedheat exchange fluid from the reservoir into the heat exchanger and asecond feed pump connected to withdraw the heat exchange fluid from theheat exchanger.

Further aspects of the invention and features of specific embodiments ofthe invention are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate non-limiting embodiments of the invention:

FIGS. 1A, 1B and 1C are respectively a longitudinal elevationalcross-section view; a top plan view and a bottom plan view of a flexibleheat exchanger configured as a cooling/warming pad for a subject's neck;

FIGS. 2A, 2B and 2C are respectively a cross-section view; a bottomview; and a top view of the flexible heat exchange plate of a heatexchanger according to an alternative embodiment of the invention;

FIG. 2D is a partial view of the outside surface of a heat exchangerhaving thermally-conductive members arranged in a triangular array;

FIG. 2E is a partial view of the outside surface of a heat exchangerhaving thermally-conductive members arranged to provide converging linesof flexible material;

FIG. 2F is a view of the outside surface of a heat exchanger havingthermally-conductive members arranged in a rectangular array oriented atan angle to a long axis of the heat exchanger;

FIGS. 3A, 3B and 3C are respectively a cross-section view; a bottomview; and a top view of the flexible heat exchange plate of a heatexchanger according to one embodiment of the invention;

FIGS. 4A through 4L are views of different heat conductors that can beused in heat exchangers according to different embodiments of theinvention;

FIGS. 5A and 5B are respectively sectional and bottom views of aflexible plate of a heat exchanger according to another embodiment ofthe invention;

FIG. 6 is a section through a heat exchanger according to anotherembodiment of the invention. FIGS. 6A, 6B and 6C are respectively across section in the plane 6A-6A, a bottom plan view, and a horizontalsection through the heat exchanger of FIG. 6 (with the rear membraneremoved);

FIGS. 6D, and 6E illustrate a heat exchanger in which a pattern of seamsprovides a U-shaped channel; FIG. 6F shows another heat exchanger inwhich a pattern of seams provides two separate fluid paths through theheat exchanger;

FIGS. 7A through 7P illustrate some alternative constructions forthermally-conductive members;

FIG. 8A illustrates a number of alternative configurations for a pin ina thermally-conductive member; FIG. 8B illustrates a number ofalternative configurations for a base in a thermally-conductive member;FIG. 8C illustrates a number of alternative configurations for aretention member; FIG. 8D illustrates a thermally-conductive memberhaving a projecting sealing ring; FIG. 8E shows some possible surfaceconfigurations for bases of thermally-conductive members; FIG. 8F showsa construction which includes a compliant washer;

FIGS. 9A through 9F illustrate some alternative constructions forthermally-conductive members;

FIG. 10A shows a few possible alternative configurations for a pin in athermally-conductive member; FIG. 10B shows a few possible shapes for apin in a thermally-conductive member; FIG. 10C shows a few possibleconfigurations for retainers for thermally-conductive members of thetypes shown in FIGS. 10A and 10B;

FIGS. 11A through 11E illustrate extensions which may be attached tothermally-conductive members to provide enhanced thermal contact with acirculating fluid;

FIGS. 12A through 12C illustrate thermal conduction members according toother alternative embodiments of the invention;

FIG. 13 is a cross section through a pin passing through a membranebefore the pin is deformed to seal to the membrane;

FIG. 13A is a top plan view of the pin of FIG. 13;

FIG. 14 is a cross section through the pin of FIG. 13 while the pin isbeing deformed and the membrane is being carried into a groove on thepin;

FIG. 15 is a cross section through the pin of FIG. 13 after the pin hasbeen deformed to seal to the membrane;

FIG. 15A is an enlarged view of one of the grooves shown in FIG. 15;

FIGS. 16A, 16B, 16C, 16D, 16E and 16F are detailed views of alternativeconfigurations for the edge of a membrane retention groove;

FIG. 17 illustrates a two-part through member according to analternative embodiment of the invention;

FIGS. 18A, 18B and 15C are cross sectional views of three throughmembers according to alternative embodiments of the invention;

FIGS. 19A, 19B and 19C demonstrate the use of a through member accordingto the invention to join together two or more thin flexible sheets;

FIGS. 20A, 20B, 20C, 20D and 20E show a through member according to analternative embodiment of the invention; and, FIG. 21 shows a throughmember according to another alternative embodiment of the invention.

FIGS. 22, 22A and 22B illustrate heat exchangers having rear sheetsaffixed to thermally-conductive members;

FIGS. 23A and 23B illustrate embodiments of the invention in which innerand outer surfaces of a membrane have different characteristics;

FIGS. 24, 25, and 26 are schematic views of cooling systems according tothe invention;

FIG. 27 shows a heat exchanger adapted for cooling or warming the neckof a subject;

FIGS. 28A, 28B and 28C show a heat exchanger like that of FIG. 27 inposition on the neck of a subject;

FIGS. 29A, 29B and 29C illustrate a heat exchanger system comprising aheat exchanger configured to fit a subject's neck and another heatexchanger configured to fit the subject's face;

FIGS. 30A, 30B and 30C illustrate a heat exchanger system comprising aheat exchanger configured to fit a subject's neck, another heatexchanger configured to fit the subject's face and another heatexchanger configured to fit the subject's scalp;

FIG. 31 illustrates a heat exchanger system having heat exchangers forwarming or cooling a patient's head, torso and thighs;

FIGS. 32A, 32B and 32C illustrate various heat exchangers and fluid flowpaths of the heat exchanger system of FIG. 31;

FIGS. 33A, 33B, 33C and 33D are schematic views of heat exchangersaccording to embodiments of the invention being applied to coolingvarious objects;

FIGS. 33E and 33F show heat exchangers having thermally conductivemembers shaped to conform with a surface of an object to be cooled;

FIG. 33G shows thermally-conductive members having ends shaped invarious ways;

FIG. 34 illustrates a heat exchanger according to an embodiment of theinvention being used to cool a high-temperature object;

FIGS. 35A and 35B show heat exchangers according to alternativeembodiments of the invention

FIG. 36A is a top plan view of a heat exchange pad according to anembodiment of the invention;

FIG. 36B is a bottom plan view of the heat exchange pad of FIG. 36A;

FIG. 37A is a longitudinal section through the heat exchange pad of FIG.36A;

FIG. 37B is an enlarged portion of FIG. 37A;

FIG. 37C is an enlarged portion of FIG. 36A;

FIG. 37D is a transverse section through the heat exchange pad of FIG.36A;

FIG. 37E is an enlarged portion of FIG. 37D;

FIG. 37F is an enlarged top plan view of a heat exchanger according toan alternative embodiment of the invention;

FIG. 37G is a top plan view of a heat exchange pad according to anotheralternative embodiment of the invention;

FIGS. 38A, 38B and 38C are respectively a side elevation view, anelevational cross section view, and a transverse cross section viewthrough a heat exchange pad according to the invention wrapped around anouter surface of a cylindrical object;

FIGS. 39A, 39B and 39C are isometric views of three different thermalreservoirs having integrated heat exchangers;

FIGS. 39D, 39E and 39F are respectively a top plan view, a longitudinalelevational section, and a transverse elevational section of a thermalreservoir according to another embodiment of the invention;

FIGS. 39G and 39H are respectively a longitudinal elevational section,and a transverse elevational section of a thermal reservoir according toanother embodiment of the invention;

FIG. 40A through 40E are schematic views illustrating cooling andheating systems according to various embodiments of the invention;

FIG. 41 is a schematic view illustrating a cooling system that uses agaseous heat exchange fluid; and, FIGS. 42A, 42B and 42C arerespectively a longitudinal section, a transverse section and anenlarged view of a portion of a transverse section of a heat exchangepad according to an alternative embodiment of the invention.

DESCRIPTION

Throughout the following description, specific details are set forth inorder to provide a more thorough understanding of the invention.However, the invention may be practised without these particulars. Inother instances, well known elements have not been shown or described indetail to avoid unnecessarily obscuring the invention. Accordingly, thespecification and drawings are to be regarded in an illustrative, ratherthan a restrictive, sense.

One aspect of this invention relates to pads useful for transferringheat between a body and a heat exchange fluid. Where the heat exchangefluid is warmer than the body, the pad facilitates heat flow from theheat exchange fluid into the body and the pad serves to warm the body.When the heat exchange fluid is cooler than the body then the padfacilitates heat flow from the body into the heat exchange fluid and thepad serves to cool the body.

The heat exchange fluid may comprise a liquid, of which water is anexample, or a gas, of which air is an example. The heat exchange fluidis provided at a suitable temperature by a suitable temperature controlsystem.

Some embodiments of this invention provide flexible heat exchangerssuitable for use in warming or cooling living subjects. Heat exchangersaccording to the invention have a flexible heat exchange plate. Aplurality of thermal channels pass through the flexible heat exchangeplate. The flexible heat exchange plate has a plurality ofthermally-conductive members projecting through a flexible medium thatis essentially fluid-impermeable. The thermally-conductive membersprovide effective means to accept heat from a higher-temperature side ofthe medium, channel the heat through the medium, and release the heat ona lower-temperature side of the medium.

An outer side of the flexible heat exchange plate can be brought intocontact with a living subject. The thermally-conductive members contactthe skin of the subject. In preferred embodiments, an inner side of theflexible heat exchange plate forms one side of a channel which carries aheat exchange fluid. Heat can be exchanged between the heat exchangefluid and the subject's skin at a high rate by way of thethermally-conductive members which extend directly from the subject'sskin into the heat exchange fluid.

The thermally-conductive members may be made of any suitablethermally-conductive materials including thermally-conductive metals,for example, aluminum, copper, gold, silver, or alloys of these metalswith one another and with other metals. The thermally-conductive membersmay also be made of non-metals which have high thermal conductivitiessuch as carbon, suitable grades of graphite, diamond, sapphire or thelike. Preferably the thermally-conductive members are made frommaterials having thermal conductivities, k, of at least 50 Wm⁻¹K⁻¹ andpreferably at least 100 Wm⁻¹K⁻¹. All other factors being equal, it isdesirable that the material from which the thermally-conductive membersis made be relatively low in density to reduce the weight of heatexchangers according to the invention. Where a heat exchanger is made ina way that involves deforming the thermally-conductive members, thematerial of the thermally-conductive members is chosen to be malleable.For many applications, aluminum is a good choice for the material ofthermally-conductive members. For many embodiments, soft 1300 seriesaluminum is a good choice of material for the thermally-conductivemembers.

The thermally-conductive members are sized and located to permit thethermally-conductive plate to be flexed sufficiently to conformsubstantially to a part of a body of a living subject. Thethermally-conductive members are dimensioned and distributed in a mannerso that the thermally-conductive members cover a large proportion of thearea of the outer side of the flexible heat exchange plate. In certainembodiments of the invention a plurality of the thermally-conductivemembers cover more than 30% of an area of the outer side of the flexibleheat exchange plate. In some embodiments 50% or more of an area of theouter side of the flexible heat exchange plate is covered by thethermally-conductive members.

In preferred embodiments of the invention a plurality of thethermally-conductive members have thermally-conductive pins, fins, barsor the like that project into the volume of a heat exchanger to form anefficient heat exchange interface with heat exchange fluid in thevolume. The projecting pins, fins, bars, plates or the like that form aheat exchange interface with the fluid inside the volume of a heatexchanger may or may not be similar in shape or other physicalcharacteristics to the pins, fins, bars, plates or the like that extendthrough the flexible medium to form a thermal channel through themedium.

The following example embodiments of the invention will be described inthe context of cooling a living subject. Embodiments of the inventioncould also be applied to warming a subject. As noted below, embodimentsof the invention could also be applied to heating or cooling objects inother fields.

FIGS. 1A through 1C show a heat exchanger 10 according to an embodimentof the invention. Heat exchanger 10 has a flexible heat exchange plate12 penetrated by a number of thermally-conductive members 14. Plate 12has an outer face 16 and an inner face 18. Heat exchanger 10 has aninside volume 20 and ports 22, 23 by way of which a heat exchange fluidcan flow through volume 20. Volume 20 is defined on a front side byplate 12 and on a rear side by a rear wall 24. Side walls 25 extendbetween plate 12 and rear wall 24. Plate 12, rear wall 24 and side walls25 are all flexible so that the outer surface 16 of heat exchanger 10can conform to the local contours of a portion of a subject's body to becooled or heated.

Thermally-conductive members 14 pass through the material 30 of plate12. Inside ends 26 of thermally-conductive members 14 project intovolume 20. Ends 26 preferably project significantly into volume 20. Inthe illustrated embodiment, ends 26 are cut away to provide increasedsurface area for heat transfer with fluid in volume 20. Each inner end26 comprises a number of prongs 27. Outer faces 28 ofthermally-conductive members can be placed against the skin of asubject. Outer faces 28 may be outer faces of thermally-conductivebodies (which may be called “bases”) 29. Bases 29 are separatedsufficiently to permit heat exchanger 10 to flex in a desired degree butare preferably closely spaced to maximize the area of outer faces 28that can be placed against a desired region on a subject. For example,in some embodiments, bases 29 are spaced apart from one another byspacings in the range of 0.5 mm to 5.0 mm.

In some embodiments, each base 29 has a thickness in the range of 0.5 mmto 5 mm. For example, in some embodiments base 29 has a thickness in therange of 1 mm to 2.5 mm. The size and dimensions of base 29 in the planeof plate 12 may be chosen to suit the application, and particularlydepends on the contour of the object to be cooled or heated.Thermally-conductive members 14 according to some embodiments of theinvention for use in cooling/warming pads for human subjects, have bases29 having areas in the range of 1 mm² to 400 mm². For suchcooling/heating pads the area is preferably in the range of 10 mm² to100 mm².

Thermally-conductive members 14 may have reduced cross sectional areasin their portions inward from bases 29. The cross-sectional area ofthermally-conductive members 14 at the point that thermally-conductivemembers 14 emerge from material 30 on the inside face of plate 12 may,for example, be in the range of 20% to 100%, and preferably 35% to 65%,of the area of base 29.

Plate 12 comprises a flexible sheet or membrane through whichthermally-conductive members 14 project. The membrane may be made of aflexible material or materials 30. Thermally-conductive members 14 havelengths sufficient to pass through material 30. In preferredembodiments, members 14 project into volume 20. Thermally-conductivemembers 14 may, for example, project into volume 20 for a distance inthe range of 0 mm to 20 mm. In some embodiments intended for warming orcooling a living subject, thermally-conductive members 14 project intovolume 20 for a distance in the range of 2 mm to 10 mm. In someembodiments members 14 project past material 30 by at least 3 mm. Theportions of members 14 which project into volume 20 may also function assupports to maintain a minimum spacing between rear wall 24 and plate12.

It is not necessary that all thermally-conductive members 14 beidentical or that all thermally-conductive members 14 have equal-sizedbases 29 although it is convenient to make heat exchanger 10 withthermally-conductive members 14 substantially the same as one another.

Material 30 constitutes a flexible membrane through whichthermally-conductive members 14 extend. In some embodiments, rear wall24 is made of material 30. Substantially all of heat exchanger 10,except for thermally-conductive members 14, may be made of the samematerial or materials 30. Material 30 is preferably flexible and/orelastically stretchable. Material 30 may, for example, comprise any of avariety of suitable flexible polymers such as natural rubber,polyurethane, polypropylene, polyethylene, ethylene-vinyl acetate,polyvinyl chloride, silicone, a combination of these materials, a coatedfabric, or the like. Material 30, or portions of material 30 mayoptionally be loaded with particles of one or more thermally-conductivematerials such as metal or graphite. However, since material 30 is notrequired to play a significant role in conducting heat, material 30 maybe a material having a low thermal conductivity not exceeding 5 Wm⁻¹K⁻¹without significantly impairing the function of heat exchanger 10. Insome embodiments, material 30 has a hardness in the range of 10 to 80 onthe Shore A hardness scale.

One specific example embodiment of the invention is constructed as shownin FIGS. 1A to 1C and is designed to be applied to the neck of a humansubject to cool the subject's brain. This embodiment of heat exchanger10 has approximately 50 thermally-conductive members 14 arranged in arectangular array. Each member 14 has nine pins which project intovolume 20. Bases 29 have areas of about 10 mm×10 mm and thicknesses ofabout 2 mm. Each of the pins has a diameter of about 1.8 mm. The totallength of each of the pins is about 10 mm. The thickness of material 30in the walls of heat exchanger 10 is about 4 mm. Two short tubes ofapproximately 10 mm inner diameter provide inlet and outlet ports 22 and23. A heat exchange fluid 65 such as cold water may be circulatedthrough volume 20.

Two such heat exchangers may be dimensioned so that they can be appliedto a subject's neck respectively over the left and right carotidarteries to cool the subject's brain by cooling blood flowing to thesubject's brain. The heat exchangers are sufficiently flexible toconform substantially to the curvature of the subject's neck withoutcausing unacceptable pressure spots. The heat exchangers may be held inplace under a collar, such as a foam collar.

Plate 12 may be fabricated using any suitable process. For example,plate 12 may be made by making holes in a sheet of material 30 andinserting thermally-conductive members 14 through the holes. The holesmay initially have dimensions smaller than corresponding dimensions ofthermally-conductive members 14 so that material 30 seals aroundthermally-conductive members 14 sufficiently to prevent any significantloss of heat exchange fluid from volume 20. Additionally, or in thealternative, a sealant, such as a suitable glue may be provided toenhance the seal between thermally-conductive members 14 and material30. Plate 12 may also be made by a suitable plastic manufacturingprocess such as thermal injection molding, reaction injection molding,compression molding, vacuum forming or casting. In this case,thermally-conductive members 14 may be molded into plate 12.

The thickness of material 30 in plate 12 can be selected to provide adesired compromise between flexibility and durability. Since heatexchanger 10 does not rely on material 30 to conduct heat, it is notnecessary to make material 30 extremely thin to improve heat conduction.Material 30 may, for example, have a thickness in the range of about 0.1mm to 20 mm. In some embodiments of the invention, material 30 has athickness in the range of 4 mm to 7 mm in plate 12. Whenthermally-conductive members of types which grip material 30 from eitherside (as shown for example in FIG. 4I to FIG. 4L or 7A to 7P) are used,the thickness of material 30 may be smaller, for example, as little asabout 1 mm in plate 12.

Projections of material 30 or some other material may optionally extendinto volume 20. Such projections may be positioned to support wall 24relative to plate 12, to direct the flow of fluid 65 within volume 20and/or to induce turbulence at selected locations in the flow of fluid65 in order to provide enhanced thermal contact betweenthermally-conductive members 14 and fluid 65.

Thermally-conductive members 14 may be arranged in a wide range ofpatterns. For example, as shown in FIGS. 1A to 1C and 3A to 3C, members14 may be arranged in a number of rows and columns to form a rectangulararray, which could be a square array. In some embodiments, members 14are arranged in rows or columns which are shifted relative to oneanother as shown in FIGS. 2B and 2C. This arrangement creates increasedturbulence in fluid 65 flowing through volume 20 and hence increases theefficiency of heat transfer between the inside ends ofthermally-conductive members 14 and fluid 65. In some embodiments, bases29 of members 14 are arranged in a rectangular array as illustrated, forexample, in FIG. 1, while portions of members 14 which project intovolume 20 are arranged in rows or columns which are shifted relative toone another as shown in FIGS. 2B and 2C. In some embodiments, members 14are arranged in a triangular array, as shown in FIG. 2D.

Flexing of plate 12 may be facilitated by arranging members 14 toprovide substantially unbroken lines 31 of material 30 extendinggenerally parallel to one or more axes about which a user may wish toflex heat exchanger 10. The embodiment shown in FIG. 1B shows two setsof lines 31 of material 30 which extend between adjacent rows andcolumns of members 14. The embodiment illustrated in FIG. 2B has one setof parallel lines 31. Lines 31 are not necessarily parallel to oneanother. For example, FIG. 2E illustrates an arrangement of members 14which facilitates flexing in such a way as to conform to a portion ofthe surface of a cone. The array of members 14 is not necessarilyaligned with any axis of heat exchanger 10. For example, FIG. 2F showsthe outside face of a heat exchanger wherein thermally-conductivemembers 14 are arranged in a rectangular array oriented at an angle, φ,to a long axis of the heat exchanger.

FIGS. 1A to 1C and 2A to 2F illustrate heat exchangers in which faces 28are substantially flush with material 30 on outer face 16. Thisarrangement facilitates cleaning, as outer face 16 is substantiallysmooth. FIGS. 3A to 3C illustrate an alternative embodiment of theinvention wherein base 29 is not embedded in material 30. In thisembodiment faces 28 are spaced outwardly from material 30. Theembodiments illustrated in these Figures can be fabricated, for example,by inserting thermally-conductive members 14 though holes formed in asheet of material 30.

Thermally-conductive members 14 may take any of a wide variety of formswhich provide the function of carrying heat in either direction betweena subject on one side of the flexible plate and a heat exchange fluid 65or other matter on an opposed side as the flexible plate that is warmeror cooler than the subject. Ideally, members 14 provide:

-   -   good thermal interfaces between the thermally-conductive members        and the subject to be cooled or warmed;    -   good thermal channels across flexible material 30; and    -   good thermal interfaces between the thermally-conductive members        and the fluid in volume 20 of the thermal exchanger.        Some possible forms for members 14 are illustrated in FIGS. 4A        through 4L. It is understood that these are possible forms and        are included only as examples. Modifications to these examples        can be made to obtain a much larger list of examples. In        addition, features illustrated in these examples can be        exchanged or combined partially or fully to obtain an even        larger list of examples.

FIG. 4A shows a thermally-conductive member 14A having a square base 29and cylindrical pin 32. Pin 32 can carry heat through material 30 andconstitutes a means for channelling heat through flexible material 30and releasing heat into (or taking heat from) fluid in volume 20 of aheat exchanger. FIG. 4B shows a thermally-conductive member 14B having acircular base 29 instead of a square base. It is generally preferablethat the thermally-conductive surfaces that contact a subject's skin berounded and not have sharp corners.

FIG. 4C shows a thermally-conductive member 14C wherein both base 29 andthe pin 32 are square in cross-section (like the thermally-conductivemembers of FIGS. 2A to 2C). FIG. 4D shows a thermally-conductive member14D similar to member 14A except that pin 32 has a circumferentialgroove 33 in its part close to base 29. Groove 33 receives extramaterial 30 in an injection molding or casting process to better sealmember 14D to material 30. FIG. 4E shows a thermally-conductive member14E wherein a tip of pin 32 is tapered to facilitate insertion into ahole in a sheet of material 30.

FIG. 4F shows a thermally-conductive member 14F having a pair ofplatelike rectangular conductors 34 which serve both as thermal channelsthrough material 30 and as structures for releasing heat into (or takingheat from) volume 20. Conductors 34 may be arranged in a V-shape tobetter transfer heat to fluid flowing past plates 34. Plate-likeconductors could also be arranged in other manners such as beingparallel with each other. Thermally-conductive member 14F has theadvantage in manufacturing that it can be made by cutting and foldingthermally-conductive sheet material.

FIG. 4G shows a thermally-conductive element 14G having a thermalchannel portion provided by a tubular pin 36. FIG. 4H shows athermally-conductive member 14H having multiple pins 38 extending frombase 29. Pins 38 provide multiple thermal channels extending from thesame base 29 and projecting into the volume 30. Conductive member 14Hadvantageously provides increased contact area between conductive member14H and a heat transfer fluid 65 in volume 20. FIGS. 41 and 4J show athermally-conductive member 14I that is designed to reduce thepossibility of fluid leaking between material 30 and member 14I. Member14I may be fabricated in two-pieces 14I-1 and 14I-2 that can beassembled together in a manner that provides good thermal contactbetween pieces 14I-1 and 14I-2.

In the illustrated embodiment, one of the pieces of member 14I has a pin39 which is received in a corresponding socket 40 (see FIG. 4J) in theother piece. Pin 39 may have an interference fit in socket 40 to keepthe two pieces tightly together and to provide good heat transferbetween the pieces. A circumferentially extending groove 41 is definedbetween pieces 14I-1 and 14I-2. Groove 41 receives material 30. Thefaces of pieces 14I-1 and 14I-2 which contact material 30 may beundercut to provide ridges 42 which help to prevent fluid from leakingpast member 14I. The pieces of multi-piece thermally-conductive membersmay be fastened together in other ways which provide thermal contactbetween the pieces. For example, fastening means such as screws, rivets,or the like may be provided. FIGS. 4K and 4L show a thermally-conductivemember 14K that is similar to member 14I but is an integral part. Member14K is designed to be cramped onto material 30. Material 30 projectsinto a groove 43. The sides of the groove 43 may be cramped together tohold material 30 around the edges of member 14K as shown in FIG. 4L.

FIGS. 5A and 5B show a flexible fluid heat exchanger 50 which isnormally curved in the absence of applied forces. Heat exchanger 50 maybe used to apply heat to or to cool a substantially cylindrical objectsuch as a subject's limb. Apart from being curved, heat exchanger 50 issimilar to heat exchanger 10 of FIGS. 1A through 1C.

FIGS. 6 through 14B illustrate various embodiments of heat exchangeraccording to the invention in which thermally-conductive members extendthrough apertures in a fluid impermeable membrane and are held in placeby retention members. FIG. 6 shows a heat exchanger 110 having a volume120 defined within a membrane 130. Membrane 130 comprises a layer of asuitable flexible fluid-impermeable material. Membrane 130 has athickness adequate to provide a desired strength. Membrane 130 may bethin. For example, in some embodiments, membrane 130 has a thickness of0.010 inches or less.

Membrane 130 may comprise, for example, a suitable grade of polyurethaneor other suitable thermoplastic polymer. Examples of other materialsthat may be suitable for use as membrane 130 include: styreniccopolymers; suitable grades of: polyvinyl chloride (PVC); polyolefinssuch as polyethylene or polypropylene; styrenics such as polystyrene;polyesters such as polyethylene terephthalate (PET); polyethers such aspolyetheretherketone (PEEK); polyamides (e.g. NYLON™); silicone;cellophane; cellulose acetates; natural or synthetic rubbers;ethylene-vinyl acetate; neoprene; polytetrafluoroethylene (PTFE e.g.TEFLON™); plasticized metallic films; combinations of two or more ofthese materials; coated or impregnated fabrics; and the like.

Thermally-conductive members 114 penetrate membrane 130. Eachthermally-conductive member 114 has a pad (which may also be called abase) 129 on an outer side of membrane 130 and a pin portion 132 whichprojects into volume 120 and is in thermal contact with a fluid 65 involume 120. Base 129 may be a body formed in or attached tothermally-conductive member 114. Thermally-conductive members 114 areheld in place by retention members 115.

As shown in FIGS. 6A, 6B and 6C, membrane 130 may be affixed to itself,for example by adhesive bonding or by welding at seams 117, to formchannels 119. In the embodiment illustrated in FIGS. 6 through 6C, frontand rear sheets 130A and 130B of membrane 130 of heat exchanger 110 arejoined together in a pattern which provides a single sinuous channel 119which extends between ports 122 and 123. Ports 122 and 123 are attachedto membrane 130 with a suitable fluid-impermeable attachment means suchas welding, suitable adhesive, stitching, taping, or the like. Front andrear sheets 130A and 130B are not necessarily equal in thickness. Insome embodiments, front sheet 130A is thicker than rear sheet 130B.

In a currently preferred embodiment of the invention, rear sheet 130B isvacuum formed, or otherwise shaped, to provide a dimple corresponding toeach of the thermally-conductive members (e.g. 114).Thermally-conductive members 114 project into the corresponding dimples.This can yield a structure which remains highly flexible and resistantto “ballooning” as heat exchange fluid 65 is pumped through it. Withthis construction the volume surrounding thermally conductive members114 can be made small, thereby reducing the weight of the fluid-filledheat exchanger. Front and rear sheets 130A and 130B may be affixedtogether at locations which define one or channels which each have asingle row of thermally-conductive members extending along the channels.The locations at which front and rear sheets 130A and 130B are affixedtogether may be just far enough apart to be on either side of thethermally-conductive members 114. The channels may be straight,serpentine, U-shaped, or follow alternative paths as convenient for theapplication at hand. One can appreciate that as one moves along thecenterline of one of the channels the rear sheet 130B bumps away fromthe front sheet 130A in each dimpled portion and is close to, eventouching or almost touching front sheet 130A in its portions betweenthermally-conductive members 114.

In some embodiments of the invention, the heat exchanger has “drape”.This means that when the heat exchanger is placed over a horizontalmember, such as a thin horizontal dowel or a pencil, the overhangingparts of the heat exchanger hang down substantially vertically from thehorizontal member. A heat exchanger which has drape can conform readilyto the surface contours of a person or object against which it isbrought.

FIGS. 6D and 6E illustrate a heat exchanger in which the pattern ofseams 117 provides a U-shaped channel 119. By comparing FIGS. 6A through6C to FIGS. 6D and 6E it can be seen that the width of channel 119 maybe varied. In some embodiments channel 119 is narrow and accommodatesonly a single row of thermally-conductive members 114. In otherembodiments, channel 119 is wider and can accommodate severalthermally-conductive members 114 side-by-side. As described above, thereare many variations in the placement of thermally-conductive members114. FIG. 6F shows another heat exchanger in which a pattern of seams117 provides two separate paths through the heat exchanger. Each pathhas ports which provide an inlet and outlet for the path.

FIGS. 7A and 7B illustrate a thermally-conductive member 114A. As shownin FIG. 7A, thermally-conductive member 114A has a shoulder 121 whichprojects through membrane 130 and through an aperture 115A in retentionmember 115. As shown in FIG. 7B, shoulder 121 is deformed, for exampleby pressing, to firmly engage retention member 115 and to compressmembrane 130 between retention member 115 and base 129. In someembodiments, shoulder 121 initially projects past retention member 115just far enough that it provides a good seal when pressed flush withretention member 115. Aperture 115A may have various profiles, forexample, it may be tapered, as shown in FIGS. 7A and 7B orstraight-sided, as shown in FIGS. 7A-1, 7B-1, 7A-2 and 7B-2.

FIGS. 7C and 7D show a thermally-conductive member 114B. Pin 132 ofthermally-conductive member 114B has a sharp end 132A and a crosssectional profile which matches the cross sectional profile of retentionmember 115B. Thermally-conductive member 114B does not require apre-existing aperture in membrane 130. Pin 132 and retention member 115Bcooperate as a punch and die. As pin 132 is pressed into the aperture inretention member 115B through membrane 130, the end of pin 132 punchesan aperture in membrane 130 which matches the cross sectional shape ofpin 132. Pin 132 is a friction fit in the aperture of retention member115B.

FIGS. 7E and 7F illustrate an alternative thermally-conductive member114C wherein pin 132 is threaded and the retention member comprises awasher 115C which is compressed against membrane 130 by a nut 115D.

FIGS. 7G and 7H illustrate an alternative thermally-conductive member114D which is adhered to membrane 130 by a suitable adhesive.Thermally-conductive member 114D may be used with or without a retentionmember as shown in FIGS. 7G and 7H or with a retention member as shownin FIGS. 7I and 7J. In some embodiments, a retention member 115 issecured to membrane 130 with a suitable adhesive.

FIGS. 7K, 7L, 7K-1, 7L-1, 7K-2 and 7L-2 illustrate alternativeconstructions wherein pin 132 of a thermally-conductive member 114E isdeformed and shaped into a head 132B which bears against membrane 130. Awasher may be provided between head 132B and membrane 130. Thisconfiguration is the basis for a currently preferred embodiment of theinvention.

In other embodiments of the invention (not shown), a part ofthermally-conductive member 114 projects from an enlarged body in volume120 through an aperture in membrane 130. The projecting part ofthermally-conductive member 114 is subsequently deformed, for example bypressing, to form an enlarged base on the outside of membrane 130. Themembrane is held between the body in volume 120 and the enlarged base.

FIGS. 7M and 7N illustrate a construction in which athermally-conductive member 114F is held against membrane 130 by aspring clip 115-2.

FIGS. 7O and 7P illustrate a construction wherein a retaining member 115is deformed, for example by pressing, to seal against pin 132 andmembrane 130.

Many variations in the design of a thermally-conductive member 114 andretention member 115 are possible within the scope of the invention.Thermally-conductive member 114 and retention member 115 may be made ofthe same material. If they are made from different materials then it isdesirable that the coefficients of thermal expansion of the materials ofthermally-conductive member 114 and retention member 115 be such thatretention member 115 does not tend to loosen as a heat exchanger isused. For example, where a heat exchanger is to be used for coolingapplications it is desirable that retention member 115 have acoefficient of thermal expansion that is the same as or greater thanthat of pin 132.

FIG. 8A shows a few possible forms for pin 132. Pin 132 may have any ofa wide range of cross-sectional shapes. FIG. 8B shows a few possibleshapes for base 129. FIG. 8C shows a few possible configurations forretention member 115. Retention members 115-1 and 115-2 are springclips, sometimes known as push retainers. Retention members 115-1 and115-2 have inner edge portions 118 which tightly engage pin 132. Theretention member used to retain a thermally-conductive member 114typically has an outer profile which matches that of the base 129 of thethermally-conductive member 114 although this is not necessary. In someembodiments of the invention a compliant member, such as an 0-ring orcompliant washer is provided between retention member 115 and membrane130, between base 129 and membrane 130, or both. FIG. 8F shows aconstruction which includes a compliant washer.

In some embodiments of the invention, retention member 115, base 129, orboth have one or more narrow projecting rings 131 or grooves (FIG. 8D)to provide an enhanced seal with membrane 130. FIG. 8E shows somepossible surface configurations for bases 129. Bases 129 may beroughened or profiled to provide increased surface area andconsequentially improved thermal conductivity between bases 129 and anadjacent compliant surface, such as the surface of a subject's skin.

FIGS. 9A through 9F show some alternative embodiments of the inventionin which thermally-conductive members have an enlarged portion withinvolume 120 and are held to membrane 130 by a retainer located on theouter side of membrane 130. FIGS. 9A and 9B show a thermally-conductivemember 114G which comprises a pin 132 which projects into volume 120from an enlarged portion 133. A pin 135 extends from enlarged portion133 through membrane 130. Pins 132, 135 and enlarged portion 133 areconveniently integral with one another. A retainer 137 engages pin 135to hold thermally-conductive member 114G in place and sealed to membrane130. Pin 132 may project through retainer 137, as shown in FIGS. 9A and9B. In some embodiments retainer 137 covers the end of pin 132.

FIGS. 9C and 9D illustrate another thermally-conductive member 114H inwhich pin 135 is threaded and retainer 137 is in the form of a nut thatscrews onto pin 135. In the illustrated embodiment, the portion ofretainer 137 that contacts membrane 130 is smaller than thebody-contacting end of retainer 137. This enhances the flexibility ofthe heat exchanger.

FIGS. 9E and 9F show another thermally-conductive member 114I whereinretainer 137 is a press fit onto pin 135.

Many variations are possible in the embodiments of the inventionillustrated in FIGS. 9A through 9F. Pins 132 and 135 may have the samecross sectional shape, as shown in FIGS. 9E and 9F or may have differentcross sectional shapes, as shown in FIGS. 9A and 9B.

FIGS. 10A through 10C show thermally-conductive members that may be usedin embodiments like those of FIGS. 9A through 9F. FIG. 10A shows a fewpossible forms for pin 135. In the embodiments of FIG. 10A, enlargedportion and pin 132 have the same diameter. Pin 132 may have any of awide range of cross-sectional shapes. FIG. 10B shows a few possibleshapes for pin 132 in thermally-conductive members which also have a pin135. FIG. 10C shows a few possible configurations for retainers 137.

Some embodiments of the invention provide an extension on one or more ofpins 132 which provides additional surface area for thermal contact withfluid 65. The extension may be in the form of a cap affixed to the endof pin 132. Various forms of extension are shown in FIGS. 11A through11E. FIG. 11A shows an extension 141A shaped generally like a mushroomcap. FIG. 11B shows an extension 141B in the form of a cylinder. FIG.11C shows an extension 141C shaped generally like a football in sideelevation and star-shaped in cross section. FIG. 11D shows a fin-shapedextension 141D. FIG. 11E shows a tear-drop-shaped extension 141A. Theextensions may be made of the same class of materials as pins 132 andare in good thermal contact with pins 132. In some embodiments,extensions are formed integrally with pins 132.

FIGS. 12A through 12C illustrate some further alternative embodiments ofthe invention. As shown in FIG. 12A, a single base 129 may have multiplepins 132 which extend through membrane 130 and are held in place by asingle retainer member 115-3. As shown in FIG. 12B, multiplethermally-conductive members 114 may be held in place by a singleretainer member 115-4. As shown in FIG. 12C, a single base 129 havingmultiple pins 132 passing through membrane 130 may be held in place bymultiple retainer members 115-5.

FIGS. 13 to 21 show members adapted to be sealed to a membrane or otherflexible material and methods for installing such members. A number ofthe embodiments of FIGS. 13 to 21 are suitable for use asthermally-conductive members in heat exchangers according to theinvention. FIG. 13 shows a pin 210 passing through an aperture 212 in amembrane 214. Pin 210 has a head 220 on a first side 214A of membrane214. Pin 210 has a shaft 222 which extends through aperture 212 andprojects on a second side 214B of membrane 214. A groove 224 in head 220extends around the base of shaft 222. Groove 224 is wide enough toreceive an edge portion 214C of membrane 214.

As shown in FIG. 14, shaft 222 can be deformed, for example, bycompressing shaft 222 toward head 220 with a press 228. As thedeformation occurs, the material on the outside of shaft 222 in itslower portion 222A near head 222 tends to move outwardly and downwardlyas indicated by arrows 230.

Edge portion 214C of membrane 214 fits closely to shaft 222. Thedeformation of lower portion 222A of shaft 222 carries edge portion 214Cof membrane 214 into groove 224. Continued deformation of shaft 222moves edge portion 214C deeper into groove 224. Eventually the continueddeformation of shaft 222 moves inner wall 224A of groove 224 towardouter wall 224B of groove 224 so that edge portion 214C of membrane 214becomes gripped between inner wall 224A and at least a portion of outerwall 224B as shown in FIG. 15. Typically membrane 214 is gripped firstbetween inner wall 224A and corner 224C at which outer wall 224B meetssurface 220A of head 220 which surrounds groove 224.

It is thought that providing a smooth or even polished surface on theportion of shaft 222 contacted by the edge of a sheet 214 duringdeformation of shaft 222 will help the edge of sheet 214 to slide downshaft 222 into groove 224. It is also thought that the edges of sheet214 will be drawn most effectively into groove 224 if the edges of sheet214 is at least somewhat elastic.

In some embodiments of the invention, membrane 214 is impervious tofluids and pin 210 makes a fluid-tight seal to membrane 214. Membranemay be of any suitable flexible material. In some embodiments of theinvention, membrane 214 comprises an elastic material, such as urethane.Membrane 214 could comprise any of a variety of suitable flexible sheetlike materials. Some examples are polymers such as natural rubber,polyurethane, polypropylene, polyethylene, ethylene-vinyl acetate,polyvinyl chloride, silicone, a combination of these materials, fabrics,or the like.

Pin 222 may be of any suitable material which is sufficiently ductile tobe plastically deformed by pressing, as described above. Where pin 222is to operate as a thermally-conductive member in a heat exchanger thenthe material of pin 222 should be highly thermally-conductive. Forexample, pin 222 may be made of aluminum, copper, or another plasticallydeformable metal having good thermal conductivity. Other metals ormaterials commonly used to make blind or solid rivets could be used.Some examples of such metals include suitable steels, stainless steels;brasses; bronzes; monel (a nickel-copper alloy); and inconel (anickel-chromium alloy). Some successful prototypes have used 1100 seriesaluminum having a hardness of about 32 on the Brinell hardness scale forshaft 222. The other materials listed above typically have hardnesses inthe range of about 20 and about 200 on the Brinell hardness scale. Inapplications in which pin 222 is not required to conduct heat,deformable plastics such as suitable grades of polyurethane,polyethylene, polypropylene, PVC or poly carbonate could also be usedfor shaft 222.

As shown in FIGS. 16A to 16F, the profile of groove 224 may be varied.It may be desirable to provide a relieved corner or “lip” 224C whereouter wall 224B of groove 224 intersects surface 220A of head 220. Insome embodiments of the invention the main seal between pin 210 andmembrane 214 occurs at the nip 232 (FIG. 15) between corner 224C and thedeformed shaft 222. Providing a relieved corner 224C provides increasedsurface area in the seal and also facilitates membrane 214 being movedinto groove 224.

FIG. 16A shows a groove 224 having a sharp outside corner 214C. FIG. 16Bshows a groove 224 having a bevelled outside corner 214C-1. FIG. 16Cshows a groove 224 having a rounded outside corner 224C-2. FIG. 16Dshows a groove 224 wherein outside corner 224C-3 is elevated above thesurrounding surface of face 220A of head 220. FIG. 16F shows a groove224 having an outer wall 224B which is inclined away from shaft 222.

It is convenient, although not mandatory, to make head 220 and shaft 222integral with one another. Head 220, including the outer wall 224B ofgroove 224 does not need to be deformable as does shaft 222. In someembodiments, shaft 222 and head 220 could comprise separate parts whichare suitably affixed to one another. An example of such a constructionis depicted in FIG. 17.

FIG. 17 shows a through-member 240 having a first part 242 whichincludes a plastically deformable shaft 243 having an enlarged head 244at one end. A second part 245 has an aperture 246. Shaft 243 projectsthrough aperture 246. A groove 248 is defined between shaft 243 and awall 249 of a counterbored part 246A of aperture 246. Second part 245may be made of a harder material than first part 242.

FIG. 18A illustrates a through member 260 according to an alternativeembodiment of the invention in which shaft 262 is tubular. FIG. 18Billustrates a through member 264 according to another alternativeembodiment of the invention in which shaft 266 is semi-tubular. Atubular or semi-tubular shaft can be deformed with the application ofless force than would be required to deform a solid shaft made out ofthe same material.

A through member may be configured as a blind rivet. FIG. 18C shows athrough member 270 configured as one type of blind rivet. Through member270 has an actuating stud 272 passing through a hollow shaft 274.Actuating stud 272 has an enlarged head 276 and a weakened portion 278.Through member 270 can be installed by pulling on the projecting shank279 of actuating stud 272. This causes head 276 to compress shaft 274and to deform shaft 274 outwardly. As shaft 274 is deformed, a membrane214 is drawn into and becomes affixed within a groove 224 as describedabove. Eventually enough tension can be applied to shank 279 to causeactuating stud 272 to break off at weakened portion 278. In typicalembodiments, shaft 274 is a soft deformable material such as aluminum ora suitable grade of stainless steel while stud 272 is of a hardermaterial such as steel.

The invention could also be embodied in blind rivets of other typeswhich have a shaft which in deforms outwardly when the blind rivetinstalled in a manner such that a membrane 214 or other material throughwhich the blind rivet passes is moved into and retained in a groove bythe deformation of the shaft.

A through member according to the invention may be used to join togethertwo or more sheets of material. FIGS. 19A, 19B and 19C, show theapplication of a through member 280 to join together two or more sheetsof material. Through member 280 may be constructed and used as describedabove. Through member 280 is similar to the through member 210 of FIG.13 except that groove 224 has been made wider. In this embodiment,groove 224 is wide enough to receive edges 214-1C and 214-2C of each ofthe sheets 214-1 and 214-2 of material being joined together. Even wherethe sheets of material are flexible it is not necessary to provide awasher or other separate fastening component on the side of the materialsheets away from head 220. Through members according to otherembodiments of the invention described herein, including the blind rivetembodiments, could also be used to attach multiple sheets of materialtogether.

FIGS. 20A through 20E depict stages in the installation of a thoughmember 290 according to an alternative embodiment of the invention.Through member 290 has a square shaft 291 extending from a head 292. Anaperture 293 extends through shaft 291. A groove 294 extends around thebase of shaft 291. Shaft 291 passes through an aperture in a sheet 214of a flexible material.

As shown in FIG. 20C, deformation of shaft 291 causes the outward facesof shaft 291 to be tapering toward groove 294. This urges the edges ofsheet 214 into groove 294. Continued deformation of shaft 291 results inthe edges of sheet 214 being captured in groove 294 between the outerface of shaft 291 and the outside corner (or “lip”) of groove 294.

Another aspect of the invention provides a method for securing a throughmember in a membrane. The method begins with providing a through memberhaving a head, a shaft extending from the head and a groove surroundingthe shaft. The shaft is inserted through an aperture in a membrane towhich the through member is to be secured. The method continues bycompressing the shaft of the through member longitudinally and therebydeforming the shaft such that an initial deformation of the shaft movesan edge portion of the membrane into the groove of the through member.The method continues by continuing to compress the shaft longitudinallyuntil the shaft deforms sufficiently to cause the edge portion of themembrane to be gripped between an outer surface of the deformed shaftand an outer wall of the groove.

This method may be used to secure a one-piece through member securely,and in some embodiments sealingly, to a membrane or to multiplemembranes or other sheet-like materials in a single operation. It is notnecessary to assemble multiple pieces to provide the through member orto perform multiple operations (although the invention could be appliedto through members assembled from more than one part or to methodsinvolving additional steps). The through member may be introduced fromone side of the membrane (or other sheet like material(s)) to which thethrough member is being affixed. It is not necessary to introducedifferent parts of the through member from different sides of themembrane.

Head 220 may carry or be attached to some structure which is to beattached to membrane 214. For example, head 220 may carry a snap andmembrane 214 may comprise a cover for something, an article of clothing,or the like. A through member according to the invention may beapertured. A valve, stopper or orifice for allowing air, another gas ora liquid to flow through the aperture may be provided in the aperture. Athrough member may have a threaded aperture capable of receiving a screwor may have a projecting stud. A through member could carry alternativestructures such as electrical connectors. In some embodiments of theinvention the through member is electrically conductive or has one ormore electrical conductors which join electrical connectors on opposingsides of membrane 214.

Various alterations and modifications are possible in the constructionand installation of through-members as illustrated in FIGS. 13 to 20without departing from the invention. For example:

-   -   shaft 222 is not necessarily circular, as illustrated, but could        have another cross sectional shape, such as slightly elliptical        or square.    -   where a shaft has an aperture passing all or part way through        it, as shown in FIGS. 20A through 20E, for example, then the        installation method may include pressing outwardly from within        the aperture. for example, the method may include pressing a        tapered pin into the aperture.    -   the outer surface of shaft 222 is not necessarily perpendicular        to the head. For example, FIG. 21 illustrates an embodiment        wherein a lower portion 299 of a shaft 222 is tapered toward        groove 224. In this embodiment, the thickness of shaft 222        increases in the direction away from head 222. However, if        membrane 214 is elastic then membrane 214 can be pulled over        shaft 222 and still contact portion 299 closely enough to be        urged into groove 224 as shaft 222 is deformed.    -   A through member according to the invention may be attached to        sheet like materials of a wide range of types including fabrics,        membranes, leather, thin metal sheets (e.g. metal foils, shim        stock), plastic sheets, rubberized sheets and the like.

As shown in FIG. 22, rear sheet 130B of membrane 130 may be affixed tosome or all of thermally-conductive members 114. This helps to prevent“ballooning” of the heat exchanger, especially where volume 120 islarge. Any suitable means may be provided to affix rear sheet 130B tothermally-conductive members 114. For example:

-   -   rear sheet 130B may be glued to thermally-conductive members 114        using a suitable adhesive;    -   a piece of material to which rear sheet 130B may be welded may        be affixed in any suitable manner at the inner ends of        thermally-conductive members 114 and rear sheet 130B may be        welded to that piece of material; or    -   rear sheet 130B may be mechanically attached to        thermally-conductive members 114, for example: a screw, part of        the thermally-conductive member 114 or the like may pass through        an aperture in rear sheet 130B to hold rear sheet 130B against        thermally-conductive member 114; a portion of rear sheet 130B        may be pressed into an aperture on the end of        thermally-conductive member 114; or, a retaining member behind        rear sheet 130B may be held in place by deforming a portion of        thermally-conductive member 114 in a manner similar to that        illustrated in FIGS. 7K and 7L. FIGS. 22A and 22B show one        example of a mechanical means for holding rear sheet 130B to        thermally-conductive member 114.

In some embodiments of the invention it is desirable that the outersurface of membrane 130 have different properties than the surface ofmembrane 130 which faces into volume 120. For example, where a heatexchanger is intended to warm or cool a living subject it may bedesirable that the outer surface of membrane 130 be absorbent to absorbany sweat, dirt or condensation from the subject's skin. As shown inFIG. 23A, membrane 130 may be a two-ply membrane having differentsurface characteristics on its inner and outer faces.

In the embodiment of FIG. 23B, membrane 130 is made up of an innerfluid-impermeable layer 130-1 and an outer absorbent layer 130-2. Withthis construction, it is unnecessary to make fluid-impermeable layer130-1 of a material that is approved for contact with a subject or otheritem to be heated or cooled because only thermally-conductive membersand outer absorbent layer 130-2 can come into contact with the subject.As an example, layer 130-2 may comprise SOFTESSE™ material availablefrom DuPont.

Where a membrane has multiple layers, the materials of the layers may bechosen to have characteristics under compression and/or elasticcharacteristics which differ from one layer to the other. Such membranesmay be included to advantage in embodiments of the invention in whichthe membrane is compressed between parts of a thermally-conductivemember (as shown, for example, in FIG. 6A or 13 to 21). In suchembodiments of the invention, it can be desirable for the membrane toinclude a relatively soft fluid impermeable layer which can seal well tothe thermally-conductive member. However, a single-ply membrane that ishighly compressible and/or greatly compressed by a thermally-conductivemember may take on a shape which is somewhat distorted in the vicinityof the thermally-conductive member. By providing a two-ply or two-layermembrane this problem can be avoided. The membrane can combine a sealinglayer having good properties for sealing with a control layer. Thesealing layer may be highly compressible and relatively easilystretchable. The control layer may be significantly less stretchy andless compressible than the sealing layer.

For example, the sealing layer may comprise a sheet of suitable plasticmaterial, such as urethane, while the control layer may comprise a sheetof a woven or unwoven fabric. The fabric may be significantly lesselastic than the sealing layer and, in some cases may be substantiallynon-elastic under the expected conditions of use of the heat exchanger.The sealing layer may be on the inside of membrane 130 facing intovolume 120 in which case the sealing layer may be welded to a layermaking up the back side of volume 120.

In some embodiments of the invention the membrane has three layers, forexample, a compressible elastomer sealing layer; a fabric control layer;and an outer layer of a soft absorbent material that is approved forskin contact.

A suitable circulation system may be used to circulate a heat exchangefluid through the volume 20 of one or more heat exchangers as describedherein. For cooling purposes it is desirable that the temperature ofcirculating fluid 65 be greater than 0° C. to avoid freezing thesubject's skin. The desired temperature of the circulating fluid willdepend to some degree on the application and the portion of thesubject's body to be treated. The desired temperature for cold therapyranges between 0° C. and 15° C. Water has properties which make it goodfor use as a circulating fluid 65.

It is generally desirable to maintain the pressure of fluid 65 in volume20 approximately equal to the air pressure surrounding heat exchanger10. If the pressure within volume 20 is significantly smaller than theambient air pressure then pressure differences across the walls ofvolume 20 will tend to collapse volume 20 although the projecting insideends 26 of thermally-conductive members 14 may prevent the walls fromcomplete collapse. If the pressure within volume 20 is significantlylarger than the ambient air pressure then heat exchanger 10 will tend toballoon.

FIG. 24 is a schematic view of a cooling system which includes a heatexchanger 10 and a fluid circulating system 60. Circulation system 60has an insulated reservoir 62 containing a volume of ice 64. System 60contains a suitable heat exchange fluid 65, which may be liquid water.System 60 delivers fluid 65 to heat exchanger 10 through deliveryconduit 66 and returns coolant to reservoir 62 through a return conduit67.

A first feed pump 70 upstream from heat exchanger 10 delivers fluid 65from reservoir 62 to heat exchanger 10. A second feed pump 72 is locateddownstream from heat exchanger 10. Second feed pump 72 draws fluid 65from heat exchanger 10 and returns the fluid to reservoir 62. First andsecond feed pumps 70 and 72 are balanced so that within volume 20 ofheat exchanger 10 the pressure of fluid 65 is substantially equal to theambient air pressure.

One or more bypass valves may be provided to provide better control overfluid pressure within volume 20. In system 60, an adjustable bypassvalve 74 is connected between the output of first feed pump 70 andreservoir 62. Bypass valve 74 indirectly regulates the pressure withinvolume 20. When bypass valve 74 is opened, a larger proportion of fluid65 is returned to reservoir 62 by way of bypass conduit 75 and theamount of fluid 65 flowing into heat exchanger 10 is reduced. Bypassvalve 74 may be pressure-operated.

System 60 has a second bypass valve 76 connected in parallel with secondfeed pump 72. When second bypass valve 76 is open, second feed pump 72can draw fluid 65 from reservoir 62 by way of conduit 77. Opening secondbypass valve 76 increases pressure at the input of second feed pump 72and consequently increases the pressure within volume 20.

Many variations of system 60 are possible. Although two bypass valvesare shown in FIG. 24 for maximum flexibility, one bypass valve connectedparallel with either one of pumps 70 or 72 or in parallel with heatexchanger 10 may be sufficient to permit pressure inside heat exchanger10 to be maintained within a desired range. In addition, depending uponthe construction of pumps 70 and 72 and the fluid flow properties of thecircuit which includes conduits 66, 67 and heat exchanger 10 it may bepossible to maintain the fluid pressure in volume 20 within the desiredrange without the need for bypass valves 74 and 76. Where bypass valvesare provided it is not necessary that they be connected directly toreservoir 62 as illustrated. Other connections may be provided whichhave the result of maintaining pressures upstream and/or downstream fromheat exchanger 10 at values which keep the pressure within volume 20 ata desired level while maintaining fluid flow through volume 20.

In some cases it may be convenient to provide a single reservoir 62 forproviding heat exchange fluid for multiple heat exchangers 10. In suchcases it is best to provide upstream and downstream pumps 70 and 72 foreach heat exchanger 10. In the alternative, suitable manifolds, such asT-connectors, could be provided to allow a number of heat exchangers 10to be connected in parallel between a single upstream pump system and asingle downstream pump system.

FIG. 25 illustrates another fluid circulating system 60A. In system 60A,a first flow regulator 78 comprising a restrictor 80 and a bypass valve82 is provided between first feed pump 70 and heat exchanger 10. Bypassvalve 82 is connected in parallel with restrictor 80. When fluid 65 isflowing through flow regulator 78 then a pressure drop across flowregulator 78 depends upon the fluid flow rate and upon the degree towhich bypass valve 82 is open.

System 60A has a second flow regulator 79 which includes a second flowrestrictor 84 and a bypass valve 86. Bypass valve 86 is connected inparallel with restrictor 84.

In system 60A, bypass valves 82 and 86 are adjustable. The fluidpressure within volume 20 can be controlled by adjusting one or both ofbypass valves 82 and 86.

Some alternative embodiments of the invention lack one of flowregulators 78 and 79. When system 60A is connected to supply fluid 65 toa plurality of heat exchangers 10 it is preferable to provide for eachheat exchanger 10 at least one adjustable flow regulator 78 or 79located where only fluid going to or from that heat exchanger passesthrough the flow regulator. This permits the pressure within each heatexchanger 10 to be individually regulated. In the alternative, asdescribed above, suitable manifolds may be provided to split the flow offluid 65 between a number of heat exchangers 10 connected in parallel.

FIG. 26 illustrates another fluid circulating system 60B. In system 60Bthe pressure within volume 20 of heat exchanger 10 is controlled byadjusting the rate of operation of one or both of upstream anddownstream feed pumps 70 and 72. In some embodiments of the invention acontrol system simultaneously increases the rate of operation of feedpump 70 and decreases the rate of operation of feed pump 72 or viceversa. The rate of operation of pumps 70 and 72 may be controlled byadjusting the rate of rotation of motors which drive the pumps, byadjusting displacements of the pumps, or the like.

In the illustrated embodiment, control is accomplished by operating apower splitter 88 (illustrated schematically by a potentiometer). Powersplitter 88 can be operated to increase the speed of a motor drivingpump 70 and to decrease the speed of a motor driving pump 72 or viceversa.

Systems 60, 60A and 60C may be automatically controlled using anysuitable control system. For example, a controller may be provided tooperate bypass valves and/or control pump speeds or displacements by wayof suitable actuators (not shown) as necessary to control pressurewithin volume 20 to stay within a desired range. Those skilled in theart are familiar with suitable controllers. The controller may, forexample, comprise a suitable programmed programmable controller or ahardware controller. One or more pressure sensors and/or flow sensors(not shown) may be included to provide feedback to the controller.

Any of cooling systems 60, 60A and 60B could be adapted for warming byreplacing ice 64 with a suitable heating element which can be operatedto raise fluid 65 in reservoir 62 to a desired temperature. Instead ofice 64, any of systems 60, 60A or 60B could cool fluid 65 by way of arefrigeration system. However, a refrigeration system large enough toprovide high-rate cooling of a living person is expensive, consumes alarge amount of power and is not readily portable. Ice has the advantagethat melting a block of ice takes a large amount of heat. A reservoir 62containing enough ice to apply high rate cooling to a human subject fora significant period can be small enough to be readily portable.

FIGS. 27 through 32C show heat exchangers incorporatingthermally-conductive members 14 or 114 as described above. The heatexchangers may be used to cool or warm various body parts of a livingsubject. FIG. 27 shows a heat exchanger 310 adapted for cooling orwarming the neck of a subject adjacent the subject's carotid arteries.Such a heat exchanger may be used to cool blood flowing to the subject'sbrain. Heat exchanger 310 comprises two pads 310A and 310B. The pads maybe attached around a subject's neck with fasteners 313A and 313B whichmay, for example, comprise complementary hook and loop fasteners such asVELCRO™. A layer of thermally-conductive gel may be provided on the padto improve heat transfer between the subject's skin andthermally-conductive members 114. Cooling fluid may be introducedthrough an inlet port 322. The cooling fluid circulates through both ofpads 310A and 310B before exiting at outlet port 323. A tube 311 carriesfluid from pad 310A to pad 310B and a return tube 312 returns fluid frompad 310B to pad 310A.

FIGS. 28A, 28B and 28C show a heat exchanger 310 like that of FIG. 27 inposition on the neck of a subject.

As shown in FIGS. 29A through 30C, additional heat exchanger pads may beconnected in series with heat exchanger 310 to cool or warm a largerarea of the subject. FIGS. 29A, 29B and 29C show a system 318 whichincludes a pad 310C configured to be applied over a subject's face. Pad310C receives fluid from pad 310A through tube 311A and returns fluid topad 310B through tube 312A. Pad 310C is held in place by a head strap314 and a chin strap 315.

FIGS. 30A, 30B and 30C show a head cooling and/or warming system 320which includes a scalp pad 310D in addition to the pads 310A, 310B and310C of the system of FIGS. 29A through 29C. Scalp pad 310D isconfigured to conform substantially with the scalp of a subject. In theillustrated embodiment, scalp pad 310D receives fluid from face pad 310Cby way of tube 311B and returns fluid to face pad 310C by way of tube312B.

FIG. 31 illustrates a system 340 for cooling or warming multiple regionsof a subject. System 340 includes a head cooling and/or warming system320 as shown in FIGS. 30A through 30C, a torso cooling and/or warmingsystem 342 and a thigh cooling and/or warming system 344. Each ofsystems 320, 342 and 344 are connected to a source 60 of a cooled (orwarmed) fluid. The rate of flow of fluid through each of systems 320,342 and 344 may be independently regulated. In some embodiments of theinvention, a controller associated with source 60 regulates the rate offluid flow through systems 320, 342 and 344 in response to measurementsof the subject's core temperature or equivalent measurements and atarget value for the subject's core temperature.

FIG. 32A illustrates a possible arrangement of fluid passages in headcooling and/or warming system 320. FIG. 32B illustrates a possiblearrangement of fluid passages in torso cooling and/or warming system342. FIG. 32C illustrates a possible arrangement of fluid passages inthigh cooling and/or warming system 344. Thermally-conductive members114 have been omitted from FIGS. 32A through 32C for clarity.

As noted above, heat exchangers according to alternative embodiments ofthe invention may be applied to heating or cooling objects of diversetypes. For example, FIG. 33A shows a heat exchanger 10 being used tocool an electric motor 52. Bases 29 of thermally-conductive members 14contact the curved outer surface 53 of motor 52. FIG. 33B shows a heatexchanger 10 being applied to cool a compressor 54 having an outerhousing 55 which has a profile having compound curvature. Bases 29contact the surface of housing 55. Compressors having compound curvesare frequently used in refrigeration and air conditioning systems. FIG.33C and 33D show a heat exchanger 10 being applied to cool a pipe 56.Bases 29 contact an outer cylindrical surface 57 of pipe 56. Pipe 56could be an exhaust pipe, for example.

Bases 29 or 129 of thermally-conductive members of heat exchangers asdescribed herein may be shaped to better conform with a surface of anobject to be warmed or cooled. For example, FIG. 33E shows a heatexchanger in which bases 129 of thermally-conductive members 114 aremachined or otherwise shaped to provide concave faces 129A. Faces 129Aeach have a radius of curvature to match that of the cylindrical surfaceof a housing 55 of an object to be heated or cooled. On otherembodiments (not shown), thermally-conductive members 14 or 114 may havefaces shaped to provide convex surfaces of surfaces having more complexshapes to match the profile of a surface of an object to be cooled orheated. In some cases, ends of thermally-conductive members 14 or 114may be affixed, for example, with bolts or studs, to a surface of anobject to be cooled or heated.

An object to be heated or cooled may be specially configured to match aheat exchanger according to this invention. FIG. 33F shows an object tobe cooled which has sockets 55A in an outer housing 55. A heat exchangerhas thermally-conductive members 114 having bases 129 with ends 129Binserted into and shaped to conform with sockets 55A. A suitablethermally-conductive paste may be used to enhance thermal contactbetween thermally-conductive members 114 and housing 55. FIG. 33G showsthermally-conductive members having ends shaped in various ways.

FIG. 34 illustrates schematically a heat exchanger 58 being used to coolan object 59 having a temperature high enough that it could causedegradation of material 30. Heat exchanger 58 is similar to heatexchanger 10 except that bases 29 are elongated so that they contactobject 59 at a location spaced away from material 30. A heat shield 360is provided between object 59 and material 30. Thermally-conductivemembers 14 pass through the heat shield. Each of thermally-conductivemembers 14 extends through a thermally insulating sleeve 59A. Sleeves59A protect material 30 from becoming overheated through contact withmembers 14. Shield 360 protects material 30 from heat radiated by object59.

Heat exchangers may also be used to transfer heat between fluids and/orbetween solid objects. FIG. 35A shows a heat exchanger 61 comprising amembrane of a material 30 penetrated by thermally-conductive members 62.Members 62 have bodies 29 on both sides of material 30. As shown in FIG.35B, bodies 29 can optionally comprise fins, pins or otherthermally-conductive elements disposed to provide improved thermalcontact between the body 29 and a surrounding fluid. The heat exchanger61A illustrated in FIG. 35B has pins 32 projecting from each body 29.Bodies 29 are larger in area than the central portions of members 14which pass through material 30. The edges of the bodies press againstthe membrane to seal any gap between the member and the membrane so thatfluid will not leak from one side to the other.

FIGS. 36A through 37F show a pad 510 according to one embodiment of theinvention. Pad 510 has an inlet 512 for receiving a heat exchange fluid513, a path 514 along which heat exchange fluid 513 can flow, and anoutlet 516. In some embodiments, heat exchange fluid 513 is recirculatedalong a fluidic circuit extending between a temperature controller andone or more pads 510. For example, pad 510 may be used in one of thesystems for heating or cooling a body disclosed in PCT patentapplication No. PCT/CA2004/001660.

Path 514 of pad 510 is defined in a chamber 518 between a back sheet 520and a front sheet 522 that are bonded together along connection lines523. Connection lines 523 comprise locations along which back sheet 520and front sheet 522 are affixed to one another by welding, a suitableadhesive, or other suitable affixation means. Thermally-conductivemembers 524 are disposed along path 514. Each thermally-conductivemember 524 penetrates and is sealed to front sheet 522 to prevent heatexchange fluid 513 from leaking around thermally-conductive members 524.

Each thermally-conductive member 524 has an outer face 524A on a frontface of pad 510 and an inner face 524B on a part of member 524 thatprojects into chamber 518. Inner faces 524B of thermally-conductivemembers 524 are in contact with heat exchange fluid 513.Thermally-conductive members 524 may have, for example, any of theconstructions described in the above-noted PCT application.

Rear sheet 520 is formed to provide a cup 530 coinciding with eachthermally-conductive member 524. As seen best in FIGS. 37B and 37C, thecross-sectional area of path 514 alternates between cups 530 in whichthe cross-sectional area is relatively large and constricted areas 532between thermally-conductive members in which the cross-sectional areaof path 514 is relatively small. In embodiments illustrated by FIG. 37B,the clearance 535 between inner face 524B of the thermally-conductivemember 524 and rear sheet 520 is greater than the clearance between rearsheet 520 and front sheet 522 in constricted area 532. In theembodiments illustrated by FIG. 37C, the width of path 514 is greater inportions of path 514 adjacent a thermally-conductive member 524 than itis in its constricted portions 532.

In some preferred embodiments front sheet 522 and rear sheet 520 arevery flexible fluid-impermeable sheets such as thin sheets of polyetherthermoplastic polyurethane. This material has a temperature range from−60 C to 140 C. Front sheet 522 and rear sheet 520 may also be made ofother suitable materials, such as urethane, polyurethane,polyvinylchloride (PVC), rubber, silicone, or the like. Variousmaterials suitable for use as front sheet 522 and rear sheet 520 aredescribed in the above-noted PCT application. The material of rear sheet520 is preferably somewhat elastic. Urethane having a thickness ofapproximately 0.015 inches has been found to be a satisfactory materialto use for rear sheet 520.

For some applications, the thermal characteristics of the materials areimportant. For example, some polyvinylchloride materials become quitebrittle at temperatures below 5° C. Ethylvinylacetate can also becomeundesirably rigid at low temperatures. Such materials would not beoptimum choices for front sheet 522 and rear sheet 520 in applicationswhere a pad 510 is operated at lower temperatures.

Fluid flowing along path 514 encounters a pattern of alternatingconstrictions 532 and enlarged areas corresponding to cups 530. Althoughthe inventors do not wish to be bound by any particular theory ofoperation, this alternating pattern of areas of greater and lessercross-sectional area is thought to help to prevent chamber 518 frombecoming overly inflated and overly rigid as heat exchange fluid 513flows through pad 510. This pattern may also assist heat transferbetween thermally-conductive members 524 and heat exchange fluid 513.

In some embodiments of the invention the cross-sectional area of path514 in constricted areas 532 is about 50% or less, (in some embodiments25% or less, or even 10% or less) of the cross-sectional area of path514 in the vicinity of a thermally-conductive member 524. In all suchembodiments, the cross-sectional area in constricted areas 532 can besaid to be “substantially less” than the cross sectional areas adjacentthermally-conductive members 524.

The configuration of path 514 can be adjusted by altering the manner inwhich rear sheet 520 is formed. For example, making cups 530 deeperincreases the cross-sectional areas of path 514 in its parts adjacent tothermally-conductive members 524. The configuration of path 514 can alsobe adjusted by altering the paths of connecting lines 523. For example,the cross-sectional area of constricted portions 532 can be made smallerby making the opposing connecting lines 523 closer to one another.Similarly, the cross-sectional area of constricted portions 532 can bemade larger by making the opposing connecting lines 523 farther apartfrom one another.

FIG. 37F shows an alternative embodiment of the invention whereinconnecting lines 523 are straight and constricted portions 532 aredefined, in part, between opposing spot connections 523A and 523B. FIG.37G shows a pad 510A which is similar to pad 510. In pad 510A thepattern of cupped areas 530 and back sheet 520 and connecting lines 523and spot connections 523A and 523B is such that path 514 follows azig-zag course.

FIGS. 38A to 38C illustrate the fact that a pad according to theinvention can be very flexible and can be made to conform with a surfaceof a body such as the cylindrical body 540. Body 540 can be anythingthat it is desired to heat or cool with a pad 510 according to theinvention. Body 540 may be a portion of a body of a living being, suchas a human or animal, or may be a part of a device, machine or the like.

FIGS. 39A through 39C show thermal reservoirs 550A, 550B and 550C(collectively thermal reservoirs 550) as provided by another aspect ofthe invention. Each thermal reservoir 550 comprises a bladder 552containing a heat storage material, which is preferably a liquid, suchas water, that has a phase transition (e.g. freezing/melting) at atemperature in a range of interest. The heat storage material can eithertake in or give out heat.

A number of thermally-conductive members 524 penetrate the material ofbladder 552 on at least one face thereof. Thermally-conductive members524 provide paths of very high thermal conductivity between their outerfaces 524A and the heat storage material contained within bladder 552.Thermal reservoirs 550 may be used as ice packs, or may be used to warmor cool a heat exchange fluid, or the like.

Each bladder 552 is made of a suitable material (which may be a materialof the same type as used for the pads 510 described above). Whilebladders 552 are preferably flexible, in some embodiments of theinvention, bladders 552 are of a stiffer material, such as a plastic,that holds its shape.

Thermally-conductive members 524 may be arranged in any suitablepatterns on thermal reservoirs 550. Thermally-conductive members 524 maybe disposed on one or more sides of a thermal reservoir 550.

FIGS. 39D, 39E and 39F show a thermal reservoir 555 that combinesstructural features of a pad 556 that is like pad 510 of FIGS. 36A and36B, and a bladder 557 filled with a heat storage material 558. Bladder557 may, for example, be filled with water. The water may be frozen. Aheat exchange fluid may subsequently be cooled by circulating it throughpad 556.

As shown in FIGS. 39E and 39F the front sheet 522 of pad 556 forms aportion of one wall of bladder 557. Faces 524A of thermally- conductivemembers 524 are in contact with heat storage material 558. Faces 524B ofthermally-conductive members 524 are in contact with heat exchange fluid513 in pad 556. As heat exchange fluid 513 is circulated through pad 556it is either warmed or cooled. Whether heat exchange fluid is warmed orcooled depends upon the relative temperatures of the heat storagematerial 558 and the incoming heat exchange fluid 513.

In the embodiment illustrated in FIGS. 39D to 39F, bladder 557 is formedby affixing a sheet 559 to pad 556 in any suitable way. For example,sheet 559 may be welded to pad 556 to provide fluid-tight bladder 557.In the illustrated embodiment, sheet 559 has been formed (for example byvacuum forming) to allow a relatively large volume of heat storagematerial 558 to be contained in bladder 557 without distortion of frontsheet 522 of pad 556.

One or more drain ports (not shown) may optionally be provided to allowheat storage material 558 to be added or changed. In some embodiments, ahole is punched through the walls of bladder 557. Heat storage fluid 558is introduced through the punched hole. The hole is then sealed by arivet and washer as described in the appended PCT application.

FIGS. 39G and 39H show a thermal reservoir according to a furtherembodiment of the invention in which bladder 557 is roughly lenticularin cross section when filled with thermal storage material 558.

FIGS. 40A to 40E show systems for heating or cooling a living being (a“subject”) or an object which incorporate one or more heat exchangepads, as described above and/or one or more thermal reservoirs asdescribed above. FIG. 40A shows a system 560 that has a pad 510connected in a fluid circuit 562 through which a heat exchange fluid 513is circulated by a pump 564. Outer faces 524A of thethermally-conductive members 524 of pad 510 are in thermal contact withan ice pack 565. System 560 includes a heat exchanger 566, which couldcomprise another pad 510, a pad as described in PCT patent applicationNo. PCT/CA2004/001660, or some other heat exchanger. Heat exchanger 566is in contact with a body to be cooled. For example, heat exchanger 566may be in contact with a portion of a human or animal body to be cooled.

Fluid 513 passes out of pad 510 at outlet 516, along tube 567A to heatexchanger 566. Fluid 513 returns to pad 510 by way of tube 567B, pump564 and tube 567C. A controller 568 (which may comprise any suitableprogrammable controller or control circuitry, for example) senses atemperature of heat exchange fluid 513 circulating past a temperaturesensor 569 and controls pump 564 to adjust a rate of flow of the heatexchange fluid 513 to maintain a desired temperature. Additionaltemperature sensors (not shown) may be provided in other parts of fluidcircuit 562 (for example at heat exchanger 566) to provide additionalinputs to controller 568.

The provision of a pad 510 equipped with thermally- conductive members524 helps to facilitate transfer of heat from circulating heat exchangefluid 513 into ice pack 565. Apparatus 560 could use a pad of one of thetypes described in PCT patent application No. PCT/CA2004/001660 in placeof pad 510.

FIG. 40B shows a system 570 for heating or cooling that is similar tosystem 560 of FIG. 40A but differs in two respects. In system 570temperature sensor 569 senses the temperature of heat exchange fluid 513returning to pad 510 from heat exchanger 566 instead of the temperatureof heat exchange fluid being carried from pad 510 to heat exchanger 566.Also, system 570 has a thermal reservoir 555 which may be like thatshown in FIGS. 39D, 39E and 39F, for example. Thermally-conductivemembers 524 of pad 10 are in contact with thermally-conductive members524 of thermal reservoir 555.

In some embodiments of the invention, thermally-conductive members 524are arranged in complementary patterns on pad 510 and thermal reservoir555. In some embodiments of the invention, the faces ofthermally-conductive members 524 of pad 510 have shapes that arecomplementary to the shapes of the faces that they contact ofthermally-conductive members 524 of thermal reservoir 555. For example,the faces of both sets of thermally-conductive members may be flat sothat a large area of contact is made between the thermally-conductivemembers 524 of pad 510 and the thermally-conductive members 524 ofthermal reservoir 555. In some embodiments, magnets or other means maybe provided to urge the thermally-conductive members 524 of pad 510 intocontact with the thermally-conductive members 524 of thermal reservoir555 to ensure maximum surface area contact between thethermally-conductive members 524 of pad 510 and the thermally-conductivemembers of thermal reservoir 555. For example, a small rare-earth magnetmay be embedded in a thermally-conductive member 524 of pad 510 andanother small magnet of opposite orientation or a piece of ferromagneticmaterial may be embedded in the corresponding thermally-conductivemember of heat reservoir 555.

FIG. 40C shows a cooling system 572 which is similar to system 560except for the locations in circuit 562 of pump 564 and temperaturesensor 569 and the arrangement of pad 510. System 572 uses a larger pad510 than is shown in system 560. In system 572, pad 510 is wrappedaround ice pack 565. Another feature of system 572 is that heatexchanger 566 is expressly indicated as being equipped with thermally-conductive members 524.

FIG. 40D shows a heating or cooling system 574 in which heat exchangefluid circulating in pad 510 is in contact with a thermal reservoir 575having thermally-conductive members 524 on multiple faces. Thermalreservoir 575 has a first group 577 of thermally-conductive members 524on its top surface and a second group 578 of thermally-conductivemembers 524 on its bottom surface. Thermally-conductive members of pad510 are in contact with both sets of thermally-conductive members ofthermal reservoir 575 to enable a relatively high rate of heat transferbetween heat exchange fluid 513 circulating in pad 510 and the heatexchange material 558 in thermal reservoir 575.

FIG. 40E shows a system 580 for warming or cooling a person, animal orobject having an integrated thermal reservoir 555 like that shown inFIGS. 39D through 39F. A heat exchange fluid 513 is heated or cooled asit circulates through integrated thermal reservoir 555. The fluid passesthrough a heat exchanger 566 which is in thermal contact with a person,animal or object to be heated or cooled.

In alternative systems like those of FIGS. 40A to 40E, a pad 510containing a heat exchange fluid 513 could be immersed in or in contactwith a liquid that acts as a thermal reservoir. The liquid of thethermal reservoir may be at a temperature suitable to take up or giveheat to the heat exchange fluid 513 circulating in the pad 510. forexample, in some embodiments, the liquid of the thermal reservoir maycomprise a volume of cold water or ice water.

Another embodiment of the invention is illustrated by FIG. 41 whichshows a system 590 for cooling a person or object. System 590 comprisesa source 592 of compressed heat exchange fluid 593, which may comprisecompressed air, for example. An air compressor (not shown) may beprovided to fill source 592 with compressed air. Heat exchange fluid isallowed to pass through a control valve 594 into an expansion chamber596. Expansion of heat exchange fluid 593 causes heat exchange fluid 593to become cooler. The cooled heat exchange fluid 593 passes fromexpansion chamber 596 into a heat exchanger 598. Heat exchanger 598 isin contact with a person or animal or object to be cooled. After passingthrough heat exchanger 598, the heat exchange fluid may be vented asindicated at 599.

Heat exchanger 598 may comprise a pad (for example a pad 510) asdescribed herein or a heat exchanger as described in PCT patentapplication No. PCT/CA2004/001660. The heat exchanger 598 of FIG. 41 hasthermally-conductive members 524 that are in contact with heat exchangefluid 593 inside heat exchanger 598 and extend through a wall of heatexchange 598 to contact a body to be cooled.

A controller 600, which may comprise a programmable controller oranother suitable control circuit or mechanism operates control valve 594in response to a temperature sensed at temperature sensor 602.

System 590 could be used in any of many ways including to cool asubject's body in a case where cooling is required for some medicalpurpose or to provide comfort for a person in a hot environment, forexample.

In lieu of, or in addition to an expansion chamber, system 590 couldinclude a suitable “metering” device to decrease the pressure of theheat exchange fluid without the use of an expansion chamber. Forexample, system 590 may comprise an expansion valve, capillary line,etc. Such devices are known to those skilled in the fields of airconditioning and refrigeration.

FIGS. 42A, 42B and 42C are views of a pad 610 according to analternative embodiment of the invention. Pad 610 is substantiallysimilar to pad 510 shown in FIG. 37A except that, in addition tothermally-conductive members 524 passing through front sheet 522, pad610 includes additional thermally-conductive members 624 that passthrough rear sheet 520. Pad 610 can exchange heat with thermalreservoirs or other heat sources or sinks on both of its sides. Forexample, when used in a system like system 560 or 570 (see FIGS. 40A and40B) a pad 610 could be in thermal contact with ice packs, or thermalreservoirs 555 on both sides of the pad 610. In the alternative, pad 610may be immersed in a bath of liquid, in which case, the addition ofthermally-conductive members 624 provides for a higher rate of heattransfer between the liquid and a heat exchange fluid 513 circulating inthe pad 610.

Where a component (e.g. a member, pump, valve, sensor, controller,assembly, element, device, circuit, etc.) is referred to above, unlessotherwise indicated, reference to that component (including a referenceto a “means”) should be interpreted as including as equivalents of thatcomponent any component which performs the function of the describedcomponent (i.e., that is functionally equivalent), including componentswhich are not structurally equivalent to the disclosed structure whichperforms the function in the illustrated exemplary embodiments of theinvention.

As will be apparent to those skilled in the art in the light of theforegoing disclosure, many alterations and modifications are possible inthe practice of this invention without departing from the spirit orscope thereof. For example:

-   -   Thermally-conductive members 14 or 114 may have any suitable        shapes and arrangements. Those illustrated herein are but        examples.    -   Flexible material 30 may have different compositions in        different parts of a heat exchanger according to the invention.        Different suitable flexible materials 30 may be used for        material 30 in different parts of a heat exchanger.    -   A heat exchanger according to the invention is not necessarily        rectangular or parallel-sided. A heat exchanger according to the        invention could have other shapes. Heat exchangers according to        some embodiments of the invention are elongated and have fluid        inlets and fluid outlets located in areas at opposed ends of a        long axis.    -   The arrangements of heat exchangers shown in the Figures could        be applied to warm a subject instead of to cool a subject.

1. A flexible heat exchanger comprising: a volume having at least oneinlet for receiving a heat exchange fluid and at least one outlet; and,a flexible front sheet essentially impermeable to the heat exchangefluid, the front sheet carrying a plurality of substantially-rigidmembers, each of the members comprising an exposed thermally-conductivesurface on a thermally-conductive first body on an outside of the frontsheet and having a thermally-conductive portion extending from thethermally-conductive first body, through the front sheet, and into thevolume, each of the plurality of members comprising opposed grippingsurfaces held firmly against opposed sides of the front sheet.
 2. Aflexible heat exchanger according to claim 1 wherein the volume isdefined between the front sheet and a flexible rear sheet.
 3. A flexibleheat exchanger according to claim 2 wherein the rear sheet is shaped toprovide indentations at locations that are adjacent to thesubstantially-rigid members and the thermally-conductive portions of thesubstantially-rigid members project into the indentations.
 4. A flexibleheat exchanger according to claim 3 wherein wherein the members arearranged in rows to provide a plurality of substantially unbroken linesof the front sheet extending between the rows of the members.
 5. Aflexible heat exchanger according to claim 1 wherein wherein the membersare arranged in rows to provide a plurality of substantially unbrokenlines of the front sheet extending between the rows of the members.
 6. Aflexible heat exchanger according to claim 4 wherein the members arearranged in an array such that the plurality of substantially unbrokenlines of the front sheet includes first and second sets each comprisinga plurality of the unbroken lines wherein the unbroken lines of thefirst set intersect with the unbroken lines of the second set.
 7. Aflexible heat exchanger according to claim 1 having drape.
 8. A flexibleheat exchanger according to claim 1 wherein the volume comprises achannel extending from the inlet to the outlet wherein a cross-sectionof the channel varies periodically along a length of the channel.
 9. Aflexible heat exchanger according to claim 8 wherein thethermally-conductive members are spaced apart along the channel and thechannel includes constricted areas located between thethermally-conductive members.
 10. A flexible heat exchanger according toclaim 8 wherein the channel is a sinuous channel.
 11. A flexible heatexchanger according to claim 1 wherein the thermally-conductive surfaceof the first body is spaced outwardly from the outside of the frontsheet.
 12. A flexible heat exchanger according to claim 1 wherein anarea of the thermally-conductive surface of the first bodies exceeds atotal cross sectional area of the thermally-conductive portions measuredwhere the thermally-conductive portions pass through the front sheet.13. A flexible heat exchanger according to claim 1 wherein thethermally-conductive portions project into the volume past an insideface of the front sheet by distances of at least 3 mm.
 14. A flexibleheat exchanger according to claim 1 wherein the thermally-conductiveportions each have a thermal conductivity of at least 50 Wm⁻¹K⁻¹.
 15. Aflexible heat exchanger according to claim 1 wherein thethermally-conductive portions each have a thermal conductivity of atleast 100 Wm⁻¹K⁻¹.
 16. A flexible heat exchanger according to claim 1wherein the thermally-conductive portions are made of metal.
 17. Aflexible heat exchanger according to claim 16 wherein thethermally-conductive portions are made of metals selected from the groupconsisting of: aluminum, copper, gold, silver, alloys of two or more ofaluminum, copper, gold, or silver with one another and alloys of one ormore of aluminum, copper, gold, or silver with one or more other metals.18. A flexible heat exchanger according to claim 1 wherein the outsideof the front sheet is faced with an absorbent fabric and thethermally-conductive portions of the members project through theabsorbent fabric.
 19. A flexible heat exchanger according to claim 1wherein the plurality of the members covers at least 30% of an area ofthe outside of the front sheet.
 20. A flexible heat exchanger accordingto claim 2 wherein the front and rear sheets are attached to one anotherin a pattern of attached areas to provide a sinuous channel in thevolume, the sinuous channel and extending between the inlet and outlet.21. A flexible heat exchanger according to claim 20 wherein the membersare spaced apart along the channel, each of the members is located in awider portion of the channel and the channel has a plurality of narrowerportions spaced apart along the channel, the narrower portions eachlocated between an upstream one of the members and a downstream one ofthe members.
 22. A flexible heat exchanger according to claim 1 wherein,for each of the plurality of members, the sheet is received in a grooveextending circumferentially around the member.
 23. A flexible heatexchanger according to claim 1 wherein each of the plurality of memberscomprises a rivet having a head on the outside of the front sheet and awasher on an inside of the front sheet, the thermally-conductive bodycomprises a head of the rivet and the front sheet is gripped between thehead of the rivet and the washer.
 24. A flexible heat exchangeraccording to claim 1 wherein the thermally-conducting surface is eitherflush with or projects outwardly from an outside surface of the wall.